Workers using lifting equipments can be life threatening if it is not used properly. Knowledge and training would mean a better chance of avoiding accidents and a safer working condition amongst workers. Below are some of the procedures and guidance to follow:
Hoist
1. Each overhead electric hoist is equipped with a limit device to
stop the hook travel at its highest and lowest point of safe travel.
2. Each hoist will automatically stop and hold any load up to 125 percent of its rated load, if its actuating force is removed.
3. The rated load of each hoist is legibly marked and visible to the operator.
4. Stops are provided at the safe limits of travel for trolley hoist.
5. The controls of hoist are plainly marked to indicate the direction or motion.
6. Each cage-controlled hoist is equipped with an effective warning device.
7. Close-fitting guards or other suitable devices are installed on
hoists to assure hoist rope's will be maintained in the sheaf groves.
8. All hoist chains or ropes are of sufficient length to handle the full range of movement of the application while still maintaining two full wraps on the drum at all times.
9. Nip points or contact points between hoist ropes and sheaves which
are permanently located within 2.1 m of the floor, ground, or working
platform, are guarded.
10. It is prohibited to use chains or rope slings that are kinked or twisted.
11. It is prohibited to use the hoist rope or chain wrapped around the load as a substitute for a sling.
12. The operator is instructed to avoid carrying loads over people.
Cranes and Lifting Gear
1. Crane work requires good pre-planning, well-maintained equipment, skilled operators and riggers
2. Mobile effort must be placed on pre-planning for the movement and
operation of cranes and lifting appliances. All lifting equipment must
be properly maintained. Qualified and experienced operators, riggers and
banks men (signalmen) must be provided.
General Requirements
1. Each crane and lifting equipment shall have a valid test certificate and load capacity rating issued by the authority.
2. Crane operators must be competent. Each crane operator shall hold a valid license and an approved Crane Certificate for the lift capacity of the crane he operates.
3. Slingers (riggers) and banks men (signalmen) must be competent for the jobs they are assigned to perform.
4. All lifting gear, such as slings, chains, shackles and lifting beams
must have a valid test certificate, and be marked with the safe working
load.
5. Each crane shall be inspected by an authorized agent when first brought to the site and three months thereafter.
6. Operators shall perform a check of their assigned crane each day before the start of the operations.
7. All crane outdoor operations shall be stopped during thunder (electrical) storms.
Procedures for Crane Operators
1. An escort vehicle shall be provided for the movement of large cranes.
2. Before making a lift, the weight of the item to be lifted must be
known. The weight of the block and all associated lifting gear must be
calculated as a part of the load to be lifted.
3. The crane must be capable of making the lift without exceeding the
load limit of the crane, for the radius of the lift to be made.
4. Tag lines shall be used as required.
5. Ground condition must be checked. Outrigger jacks pads shall be
used. Ground compacting test may be required for heavy lifts.
6. As required and where practicable, the area of crane operations will
be roped off to prevent persons from entering into the operating radius
of the crane.
7. Crane boom and jib shall not be left in a boom-up position overnight without prior approval.
8. All tandem lifts must be approved by the company. A method statement
must be submitted that included a sketch of the tandem lift and rigging
study.
9. A trained lifting supervisor will be the competent personnel for all
lifting operations. He should wear a colored vest for easy
identification purposes.
Lifting gear
1. All lifting gears must have a test certification. The test certification must be available for inspection upon request.
2. All lifting gear shall be tagged with it's safe working load (SWL)
3. All lifting gear shall be numbered and color coded periodically to enable quick inspection.
4. All lifting gear shall be inspected by an approved inspector on a yearly schedule. A record shall be kept.
5. Steel lashing wire, bands and ropes shall not be used for lifting purposes.
6. Steel lashing wire, bands and ropes shall not be used for lifting purposes.
7. Padding will be used when lifting sharp edged materials.
Thursday, September 22, 2011
Thursday, June 25, 2009
Introduction to Washers, its duty and applications
While fastening a screws, bolts and nuts to hold, fasten, and to apply force as a means of power transmission, you may wonder why it is important to place a “washer” along with it.
It is because washer in combination with fasteners plays a very important function such that it protects the surface contact area of the nut or bolt head. To start with, the main purpose of washers is to propagate the surface area to gain more force at 45 degrees angle distribution.
In general there are several types of washers depending on the application. It is therefore very important to know each type and use in order to have a more secured work being done.
1.Split type is spring washers that absorbs shock and reduces squeaks.
2.A serrated washer serves as anti-twist lock intents to ensure screws and bolts are secured in place. For heavier loads, a Bellevue washer is used.
3.Washers in some application serve as gasket or sealant. Copper or soft material is used in order to collapse to seal. This type of is intended to a single use only. Washers are available in light, medium, and heavy duty.
4.The plain, light duty washer is used to preserve surfaces. It increases surface area for more holding force.
5.The plain heavy duty washers are also available for specific heavy duty application.
6.The Bellevue washer has tremendous compression force that is used for critical bolt locking for safety reason as in belt drives, pulleys and aeronautics application. It also serves the purpose of increasing the surface area for more holding force. Added application feature for this type is to serve as cushioning springs to compensate surface pressure like in plastic. Molds or typical application of these washers usually uses a L-6 spring steel material.
7.The Split spring washer does not lock as what we normally perceived. The Split spring serves as shock absorber for rattle, vibrating parts and therefore suppresses the noise level.
8.The Serrated, single or double toothed washer locks the fasteners in place using the serrated tooth in either external, internal or both. It is available in flat surface application, counter sink, light and heavy duty. This type of washers is what you need for locking fasteners but has a bad reputation of damaging the surface mounting area when soft.
Remember, the use of this very simple yet effective piece of material can be a life saver. It distinguishes the difference between injury and safety. It is therefore important to know its types and usage for each specific fastening application.
It is because washer in combination with fasteners plays a very important function such that it protects the surface contact area of the nut or bolt head. To start with, the main purpose of washers is to propagate the surface area to gain more force at 45 degrees angle distribution.
In general there are several types of washers depending on the application. It is therefore very important to know each type and use in order to have a more secured work being done.
1.Split type is spring washers that absorbs shock and reduces squeaks.
2.A serrated washer serves as anti-twist lock intents to ensure screws and bolts are secured in place. For heavier loads, a Bellevue washer is used.
3.Washers in some application serve as gasket or sealant. Copper or soft material is used in order to collapse to seal. This type of is intended to a single use only. Washers are available in light, medium, and heavy duty.
4.The plain, light duty washer is used to preserve surfaces. It increases surface area for more holding force.
5.The plain heavy duty washers are also available for specific heavy duty application.
6.The Bellevue washer has tremendous compression force that is used for critical bolt locking for safety reason as in belt drives, pulleys and aeronautics application. It also serves the purpose of increasing the surface area for more holding force. Added application feature for this type is to serve as cushioning springs to compensate surface pressure like in plastic. Molds or typical application of these washers usually uses a L-6 spring steel material.
7.The Split spring washer does not lock as what we normally perceived. The Split spring serves as shock absorber for rattle, vibrating parts and therefore suppresses the noise level.
8.The Serrated, single or double toothed washer locks the fasteners in place using the serrated tooth in either external, internal or both. It is available in flat surface application, counter sink, light and heavy duty. This type of washers is what you need for locking fasteners but has a bad reputation of damaging the surface mounting area when soft.
Remember, the use of this very simple yet effective piece of material can be a life saver. It distinguishes the difference between injury and safety. It is therefore important to know its types and usage for each specific fastening application.
DIY: Maintaining air conditioners
During summer, outside temperature reaching to near 40°C can be very irritating. Worst case if your air conditioner at home is not giving you the ample coolness the way it used to be. This problem is mostly encountered by people neglecting the proper maintenance procedure or simply neglect of doing it themselves. You have nothing to blame but yourself. But before you pick up that phone and start calling your repair man to do the maintenance for you, why not read further below and check if the recommended maintenance procedure would be beneficial and is easy to follow. Here are some very basic steps on how to maintain your air conditioning unit. This procedure can be applied to all standard window-type as well as standard split-type air conditioner units.
Precaution: Before doing any maintenance, switch off the main circuit breaker of the air conditioning unit on disconnect the air conditioning unit from the electrical outlet during maintenance.
1.Cleaning of air filters of split and window-type air conditioning units.
a.Switch off the air conditioning unit.
b.Gently pull out the air filter from the air conditioning unit.
c.Clean the air filter using a vacuum cleaner.
d.If the air filter is very dirty, wash it with clean water and neutral detergent (soft brush shall be used to effectively remove the dirt).
e.Dry the air filter using a soft cloth / rags.
f.Return the air filter to the air conditioning unit.
g.Switch on the air conditioning unit if necessary.
h.This procedure shall be done every 2 weeks.
2.Cleaning of evaporator and condenser coil of split type air conditioning units.
a.Remove and recover refrigerant from the air conditioning unit using refrigerant recovery equipment. (refer to procedure 5)
b.Disconnect the power supply, refrigerant lines, and drain lines from the evaporator Unit (indoor unit) and condensing unit (outdoor unit).
c.Evaporator and condensing unit shall be pulled out and place in a containment pan.
d.Fan impeller and casing (if any) of evaporator unit (indoor unit) and condensing Unit (outdoor unit) shall be dismantled and washed using clean water and neutral detergent or water soluble solution.
e.Fan motors of indoor and outdoor unit shall be dismantled (if possible) to prevent it from being damaged during coil cleaning.
f.All electrical components including fan motors of evaporator and condensing unit shall be covered with plastic or any water resistant material.
g.Rinse the evaporator and condenser coil with the manufacturers approved chemical coil cleaner (approximately 2.5 to 3 liters per TR cooling capacity).
h.Rinse the evaporator and condenser coil with sufficient water to remove the dirt and the chemical coil cleaner. Contaminated water collected in the containment pan should be disposed properly.
i.Clean the casing (indoor and outdoor unit) and air diffuser (indoor unit only) with soft cloth or rag. Use clean water and neutral detergent if dirt and stain are difficult to remove.
j.Assemble all dismantled parts of the evaporator and condensing unit.
k.Drain line of indoor unit shall be flushed with the manufacturers approved liquid de-clogger (approximately 100 to 200 ml) and clean water sufficient enough to remove the clog materials. (Contaminated water from this procedure should be disposed properly.
l.All refrigerants and drain line connections to the air conditioning unit shall be leak tested using nitrogen and water respectively as medium. (Soap solution shall be applied to refrigerant line connections to easily locate the leaks).
m.Prior to refrigerant charging, refrigerant lines shall be subjected to flushing using nitrogen gas.
n.Prepare and charge the unit with applicable refrigerant by Triple Evacuation Method.(refer to procedure 6).
o.This procedure shall be done semi annually (every 6 months).
3.Cleaning of evaporator and condenser coil of window type air conditioning units.
a.Air conditioning unit shall be pulled-out and place in a containment pan.
b.Fan impellers for evaporator and condenser coil shall be dismantled and washed with clean water and neutral detergent or water soluble solution.
c.All electrical components including fan motor shall be covered with plastic or any water resistant material.
d.Rinse the evaporator and condenser coil with manufactures approved chemical coil cleaner (approximately 2.5 to 3 liters per TR cooling capacity).
e.Rinse the evaporator and condenser coil with sufficient water to remove the dirt and chemical coil cleaner. Contaminated water collected in the containment pan shall be disposed properly.
f.Clean the casing and air diffusers using a soft cloth / rag. If dirt and stains are difficult to remove, wash it with clean water and neutral detergent or water soluble solution.
g.Assemble all dismantled parts of the air conditioning unit.
h.Drain line of the air conditioning unit shall be flushed with manufacturers approved liquid declogger (approximately 100 to 200ml) and clean water sufficient enough to remove the clog materials. Contaminated water from this procedure shall be contained and disposed properly.
i.Drain line connection shall be leak tested using water.
j.This procedure shall be done quarterly (every 3 months).
4.Replacement of Filter Dryer
a.Filter Dryer of split-type air conditioning units shall be replaced annually.
b.Replacement of the said element shall be done during the cleaning of evaporator and condensing unit.
c.Filter Dryer of air conditioning shall be replaced during breakdown maintenance.
d.Filter Dryer connections shall be leak tested as per procedure 2.
5.Recovery of Refrigerant
a.Prepare the refrigerant recovery equipment and one (1) empty cylinder tank of refrigerant.
b.Connect the refrigerant recovery equipment to the charging port of the Condensing unit. Likewise, Refrigerant Recovery Equipment shall be connected to the empty cylinder tank of refrigerant.
c.Start the Refrigerant Recovery Equipment. By-pass the lower pressure switch of the air conditioning unit by manual pressing of magnetic contactor during refrigerant recovery to prevent the compressor to stop due to low pressure refrigerant. Release the magnetic contactor when the refrigerant pressure on the gas line drops to 10 psig.
d.Close the valve of the refrigerant tank and stop the Refrigerant Recovery Equipment.
6.Preparation of Refrigerant line and charging of Refrigerant by Triple Evacuation Method
a.Connect the gauge manifold to the refrigerant lines.
b.Purge all pressure from the refrigerant lines by opening the system service valves and gauge manifold hand valves.
c.Connect the center hose of the gauge manifold to the vacuum pump.
d.Start the vacuum pump and vacuum system of approximately -29.92 in. Hg.
e.Close the gauge manifold hand valves and stop the vacuum.
f.Disconnect the center hose of the gauge manifold from the vacuum pump and connect it to a cylinder containing (R-11) refrigerant.
g.Open the cylinder valve.
h. Loosen the center hose connection at the gauge manifold. Purge the hose for a few seconds; then tighten the connection.
i.Open the gauge manifold hand valves and charge the system with (R-11) Refrigerant up to 5 psig.
j.Close the refrigerant cylinder valve and gauge manifold hand valves.
k.Disconnect the hose from the cylinder and purge the pressure from the system by opening the gauge manifold hand valves.
l. Repeat procedures c through k for three times.
m.Repeat procedure c through e.
n.Disconnect the center hose of the gauge manifold from the vacuum pump and connect it to the cylinder of applicable refrigerant.
o.Repeat procedure g through h.
p.Open the gauge manifold hand valves and charge the system with applicable refrigerant up to the standing pressure of the cylinder tank.
q.Start the air conditioning unit and add the proper charge of refrigerant
r.This procedure shall be done at an ambient temperature of not less than 34°C.
Precaution: Before doing any maintenance, switch off the main circuit breaker of the air conditioning unit on disconnect the air conditioning unit from the electrical outlet during maintenance.
1.Cleaning of air filters of split and window-type air conditioning units.
a.Switch off the air conditioning unit.
b.Gently pull out the air filter from the air conditioning unit.
c.Clean the air filter using a vacuum cleaner.
d.If the air filter is very dirty, wash it with clean water and neutral detergent (soft brush shall be used to effectively remove the dirt).
e.Dry the air filter using a soft cloth / rags.
f.Return the air filter to the air conditioning unit.
g.Switch on the air conditioning unit if necessary.
h.This procedure shall be done every 2 weeks.
2.Cleaning of evaporator and condenser coil of split type air conditioning units.
a.Remove and recover refrigerant from the air conditioning unit using refrigerant recovery equipment. (refer to procedure 5)
b.Disconnect the power supply, refrigerant lines, and drain lines from the evaporator Unit (indoor unit) and condensing unit (outdoor unit).
c.Evaporator and condensing unit shall be pulled out and place in a containment pan.
d.Fan impeller and casing (if any) of evaporator unit (indoor unit) and condensing Unit (outdoor unit) shall be dismantled and washed using clean water and neutral detergent or water soluble solution.
e.Fan motors of indoor and outdoor unit shall be dismantled (if possible) to prevent it from being damaged during coil cleaning.
f.All electrical components including fan motors of evaporator and condensing unit shall be covered with plastic or any water resistant material.
g.Rinse the evaporator and condenser coil with the manufacturers approved chemical coil cleaner (approximately 2.5 to 3 liters per TR cooling capacity).
h.Rinse the evaporator and condenser coil with sufficient water to remove the dirt and the chemical coil cleaner. Contaminated water collected in the containment pan should be disposed properly.
i.Clean the casing (indoor and outdoor unit) and air diffuser (indoor unit only) with soft cloth or rag. Use clean water and neutral detergent if dirt and stain are difficult to remove.
j.Assemble all dismantled parts of the evaporator and condensing unit.
k.Drain line of indoor unit shall be flushed with the manufacturers approved liquid de-clogger (approximately 100 to 200 ml) and clean water sufficient enough to remove the clog materials. (Contaminated water from this procedure should be disposed properly.
l.All refrigerants and drain line connections to the air conditioning unit shall be leak tested using nitrogen and water respectively as medium. (Soap solution shall be applied to refrigerant line connections to easily locate the leaks).
m.Prior to refrigerant charging, refrigerant lines shall be subjected to flushing using nitrogen gas.
n.Prepare and charge the unit with applicable refrigerant by Triple Evacuation Method.(refer to procedure 6).
o.This procedure shall be done semi annually (every 6 months).
3.Cleaning of evaporator and condenser coil of window type air conditioning units.
a.Air conditioning unit shall be pulled-out and place in a containment pan.
b.Fan impellers for evaporator and condenser coil shall be dismantled and washed with clean water and neutral detergent or water soluble solution.
c.All electrical components including fan motor shall be covered with plastic or any water resistant material.
d.Rinse the evaporator and condenser coil with manufactures approved chemical coil cleaner (approximately 2.5 to 3 liters per TR cooling capacity).
e.Rinse the evaporator and condenser coil with sufficient water to remove the dirt and chemical coil cleaner. Contaminated water collected in the containment pan shall be disposed properly.
f.Clean the casing and air diffusers using a soft cloth / rag. If dirt and stains are difficult to remove, wash it with clean water and neutral detergent or water soluble solution.
g.Assemble all dismantled parts of the air conditioning unit.
h.Drain line of the air conditioning unit shall be flushed with manufacturers approved liquid declogger (approximately 100 to 200ml) and clean water sufficient enough to remove the clog materials. Contaminated water from this procedure shall be contained and disposed properly.
i.Drain line connection shall be leak tested using water.
j.This procedure shall be done quarterly (every 3 months).
4.Replacement of Filter Dryer
a.Filter Dryer of split-type air conditioning units shall be replaced annually.
b.Replacement of the said element shall be done during the cleaning of evaporator and condensing unit.
c.Filter Dryer of air conditioning shall be replaced during breakdown maintenance.
d.Filter Dryer connections shall be leak tested as per procedure 2.
5.Recovery of Refrigerant
a.Prepare the refrigerant recovery equipment and one (1) empty cylinder tank of refrigerant.
b.Connect the refrigerant recovery equipment to the charging port of the Condensing unit. Likewise, Refrigerant Recovery Equipment shall be connected to the empty cylinder tank of refrigerant.
c.Start the Refrigerant Recovery Equipment. By-pass the lower pressure switch of the air conditioning unit by manual pressing of magnetic contactor during refrigerant recovery to prevent the compressor to stop due to low pressure refrigerant. Release the magnetic contactor when the refrigerant pressure on the gas line drops to 10 psig.
d.Close the valve of the refrigerant tank and stop the Refrigerant Recovery Equipment.
6.Preparation of Refrigerant line and charging of Refrigerant by Triple Evacuation Method
a.Connect the gauge manifold to the refrigerant lines.
b.Purge all pressure from the refrigerant lines by opening the system service valves and gauge manifold hand valves.
c.Connect the center hose of the gauge manifold to the vacuum pump.
d.Start the vacuum pump and vacuum system of approximately -29.92 in. Hg.
e.Close the gauge manifold hand valves and stop the vacuum.
f.Disconnect the center hose of the gauge manifold from the vacuum pump and connect it to a cylinder containing (R-11) refrigerant.
g.Open the cylinder valve.
h. Loosen the center hose connection at the gauge manifold. Purge the hose for a few seconds; then tighten the connection.
i.Open the gauge manifold hand valves and charge the system with (R-11) Refrigerant up to 5 psig.
j.Close the refrigerant cylinder valve and gauge manifold hand valves.
k.Disconnect the hose from the cylinder and purge the pressure from the system by opening the gauge manifold hand valves.
l. Repeat procedures c through k for three times.
m.Repeat procedure c through e.
n.Disconnect the center hose of the gauge manifold from the vacuum pump and connect it to the cylinder of applicable refrigerant.
o.Repeat procedure g through h.
p.Open the gauge manifold hand valves and charge the system with applicable refrigerant up to the standing pressure of the cylinder tank.
q.Start the air conditioning unit and add the proper charge of refrigerant
r.This procedure shall be done at an ambient temperature of not less than 34°C.
DIY : How to Test Basic Electronic Components
How to test resistors?
Read the indicated color code value then select the OHM-scale within but not way below the indicated value. A resistor is good if its resistance is close to the indicated. Tolerance should be considered with the ohmmeter reading. While, no resistance reading at all on the ohmmeter scale settings, the resistor is open. A zero resistance reading on all ohmmeter scale settings, resistor is shorted.
How to test capacitors?
In most cases, a capacitor fails due to the deterioration of the dielectric material between its plate. Defective capacitors can have an internal shorted terminals, excessive leakage and degradation of capacitance meter. Momentarily, short the terminal of the electrolytic capacitor to discharge it.
To test a capacitor, set the multi-tester to Rx 10 or Rx1K scale. Connect the tester negative probe to the capacitor positive terminal, the positive probe to the negative terminal. A good indication for electrolytic capacitor shows the meter needle deflecting towards zero and moves back again to infinite resistance position. For ceramic, Mylar and other capacitor with a capacitance with less than 1.0 uF, the meter will not deflect at all. A defective indication for an electrolytic capacitor shows that the meter will rest on zero and remain stationary at a point which is an indication that the capacitor is shorted.
How to test diodes?
Set the multi-tester knob to any of the resistance position (x1, x10, x1K or 10K ohm ). Connect the positive probe to the anode and the negative probe to the cathode. Then connect the positive probe to the cathode and the negative probe to the anode of the diode. A good indication in the first procedure will show the meter deflected very little or may not deflect at all. And in the second procedure, the meter will deflect towards zero. The actual resistance reading is the forward resistance of the diode. A defective indication shows that the meter won’t deflect at all even when the probes are reversed. Or the meter deflects at the same time or almost the same resistance reading for both steps.
How to test transistors:
Bipolar transistors are usually checked out of a circuit by means of an ohmmeter. When it is desired to check for the resistance across the transistor emitter and collector, NPN or PNP, ohmmeter probes may be connected either way. A good transistor will show above a reading above 1000 ohm.
How to determine if it is NPN or PNP transistor?
To determine the correct terminal of the transistors, set the range selector to x 1 or 10 ohm. Connect the positive probe to the emitter and the negative probe to the base of the transistor. Note the reading interchange the connection of the probes to the leads of the transistor.
Base your conclusion on the table:
POSITIVE PROBE TO: NEGATIVE PROBE TO: RESISTANCE READING: CONCLUSION:
Emitter Base Less than 150 ohm Transistor is NPN
Base Emitter Infinity Transistor is NPN
Emitter Base Infinity Transistor is PNP
base Emitter Less than 150 ohm Transistor is PNP
Some defective indications of transistors: Resistance between any pair of the terminals is less than 10 ohms. Transistor is shorted. Resistance between base and emitter or base collector for both the forward and reverse application of ohmmeter probes is infinity (meter needle don’t deflect). Transistor is open. Transistors overheats (except power transistors) during normal operating condition. transistor is shorted.
Read the indicated color code value then select the OHM-scale within but not way below the indicated value. A resistor is good if its resistance is close to the indicated. Tolerance should be considered with the ohmmeter reading. While, no resistance reading at all on the ohmmeter scale settings, the resistor is open. A zero resistance reading on all ohmmeter scale settings, resistor is shorted.
How to test capacitors?
In most cases, a capacitor fails due to the deterioration of the dielectric material between its plate. Defective capacitors can have an internal shorted terminals, excessive leakage and degradation of capacitance meter. Momentarily, short the terminal of the electrolytic capacitor to discharge it.
To test a capacitor, set the multi-tester to Rx 10 or Rx1K scale. Connect the tester negative probe to the capacitor positive terminal, the positive probe to the negative terminal. A good indication for electrolytic capacitor shows the meter needle deflecting towards zero and moves back again to infinite resistance position. For ceramic, Mylar and other capacitor with a capacitance with less than 1.0 uF, the meter will not deflect at all. A defective indication for an electrolytic capacitor shows that the meter will rest on zero and remain stationary at a point which is an indication that the capacitor is shorted.
How to test diodes?
Set the multi-tester knob to any of the resistance position (x1, x10, x1K or 10K ohm ). Connect the positive probe to the anode and the negative probe to the cathode. Then connect the positive probe to the cathode and the negative probe to the anode of the diode. A good indication in the first procedure will show the meter deflected very little or may not deflect at all. And in the second procedure, the meter will deflect towards zero. The actual resistance reading is the forward resistance of the diode. A defective indication shows that the meter won’t deflect at all even when the probes are reversed. Or the meter deflects at the same time or almost the same resistance reading for both steps.
How to test transistors:
Bipolar transistors are usually checked out of a circuit by means of an ohmmeter. When it is desired to check for the resistance across the transistor emitter and collector, NPN or PNP, ohmmeter probes may be connected either way. A good transistor will show above a reading above 1000 ohm.
How to determine if it is NPN or PNP transistor?
To determine the correct terminal of the transistors, set the range selector to x 1 or 10 ohm. Connect the positive probe to the emitter and the negative probe to the base of the transistor. Note the reading interchange the connection of the probes to the leads of the transistor.
Base your conclusion on the table:
POSITIVE PROBE TO: NEGATIVE PROBE TO: RESISTANCE READING: CONCLUSION:
Emitter Base Less than 150 ohm Transistor is NPN
Base Emitter Infinity Transistor is NPN
Emitter Base Infinity Transistor is PNP
base Emitter Less than 150 ohm Transistor is PNP
Some defective indications of transistors: Resistance between any pair of the terminals is less than 10 ohms. Transistor is shorted. Resistance between base and emitter or base collector for both the forward and reverse application of ohmmeter probes is infinity (meter needle don’t deflect). Transistor is open. Transistors overheats (except power transistors) during normal operating condition. transistor is shorted.
Safety first when using power tools
A power tool is a tool powered by an electric motor. The addition of the motor, usually electric but possibly pneumatic or hydraulic, reduces the work required by the user, and sometimes makes it possible for the user to do things that are difficult or impossible to do by hand. Virtually every type of tool can be a hand tool, although many have also been adopted as power tools which get their motive power from engines rather than from people. Examples of power tools includes; Drill, is a tool with a rotating drill bit used for drilling holes in various materials. Heat Gun is a device used to emit a stream of hot air. Sander/ Angle grinder is a power tool used to smooth wood and automotive or wood finishes.
Prior to each use, power tools should be inspected thoroughly for any damage. To do this, here are some tips:
1.Check the handle and body casing of the tool for cracks or other damage.
2.If the tool has auxiliary or double handles, check to see that they installed securely.
3.Inspect cords for defects: check the power cord for cracking, fraying, and other signs of wear or faults in the cord insulation.
4.Check for damaged switches and ones with faulty trigger locks.
5.Inspect the plug for cracks and for missing, loose or faulty prongs.
If a tool is defective, remove it from work place area, and tag it clearly "Out of service for repair". Replace damaged equipment immediately and never use defective tools "temporarily". And lastly, do not attempt to repair a defective tool; instead have it repaired by a qualified person.
Before using a powered hand tools, ensure that you have been properly trained to use the tool safely. Read the operator's manual before using the tool. Ensure that the power tool has the correct guard, shield or other attachment that the manufacturer recommends. Ensure that the tools are properly grounded using a three-prong plug and are double-insulated (labeled as such) to prevent electric shocks. Check electric tools to ensure that a tool with a 3-prong plug has an approved 3-wire cord and is grounded. Never remove the third, grounding prong from a plug. Replace open front plugs with dead front plugs. Dead front plugs are sealed and present less danger of shock or short circuit. Use only the kind of battery that the tool manufacturer specifies for the battery-powered tool that you are using. Recharge a battery-powered tool only with a charger that is specifically intended for the battery in that tool.
While using a powered hand tools, wear or use personal protective equipment (PPE) or clothing that is appropriate for the work you are doing (safety glasses or goggles, hearing protection, dust mask, gloves, safety boots or shoes, or rubber boots). Switch off the tools before connecting them to a power supply. If a power cord feels more than comfortably warm or if a tool is sparking excessively, have it checked by an electrician or other qualified person. Disconnect the power supply before making adjustments or changing accessories. Remove any wrenches and adjusting tools before turning on a tool. Eliminate octopus connections: if more than one receptacle plug is needed, use a power bar or power distribution strip that has an integral power cord and a built-in over current protection. Pull the plug, not the cord when unplugging a tool. Keep power cords away from heat, water, oil, sharp edges and moving parts. Ensure that cutting tools, drill bits, etc. is kept sharp, clean and well maintained. Store tools in a dry, secure location when they are not being used.
Tools and equipment must be in good condition to prevent injuries. Items found damaged or defective must be taken out of service immediately.
And lastly, any tools or equipment exceeding eight (8) feet in length requires at least two (2) people for material handling activities. Tools or equipment exceeding eight (8) feet in length should not be transported through areas of high risk, which are restricted in nature such as narrow hallways.
Prior to each use, power tools should be inspected thoroughly for any damage. To do this, here are some tips:
1.Check the handle and body casing of the tool for cracks or other damage.
2.If the tool has auxiliary or double handles, check to see that they installed securely.
3.Inspect cords for defects: check the power cord for cracking, fraying, and other signs of wear or faults in the cord insulation.
4.Check for damaged switches and ones with faulty trigger locks.
5.Inspect the plug for cracks and for missing, loose or faulty prongs.
If a tool is defective, remove it from work place area, and tag it clearly "Out of service for repair". Replace damaged equipment immediately and never use defective tools "temporarily". And lastly, do not attempt to repair a defective tool; instead have it repaired by a qualified person.
Before using a powered hand tools, ensure that you have been properly trained to use the tool safely. Read the operator's manual before using the tool. Ensure that the power tool has the correct guard, shield or other attachment that the manufacturer recommends. Ensure that the tools are properly grounded using a three-prong plug and are double-insulated (labeled as such) to prevent electric shocks. Check electric tools to ensure that a tool with a 3-prong plug has an approved 3-wire cord and is grounded. Never remove the third, grounding prong from a plug. Replace open front plugs with dead front plugs. Dead front plugs are sealed and present less danger of shock or short circuit. Use only the kind of battery that the tool manufacturer specifies for the battery-powered tool that you are using. Recharge a battery-powered tool only with a charger that is specifically intended for the battery in that tool.
While using a powered hand tools, wear or use personal protective equipment (PPE) or clothing that is appropriate for the work you are doing (safety glasses or goggles, hearing protection, dust mask, gloves, safety boots or shoes, or rubber boots). Switch off the tools before connecting them to a power supply. If a power cord feels more than comfortably warm or if a tool is sparking excessively, have it checked by an electrician or other qualified person. Disconnect the power supply before making adjustments or changing accessories. Remove any wrenches and adjusting tools before turning on a tool. Eliminate octopus connections: if more than one receptacle plug is needed, use a power bar or power distribution strip that has an integral power cord and a built-in over current protection. Pull the plug, not the cord when unplugging a tool. Keep power cords away from heat, water, oil, sharp edges and moving parts. Ensure that cutting tools, drill bits, etc. is kept sharp, clean and well maintained. Store tools in a dry, secure location when they are not being used.
Tools and equipment must be in good condition to prevent injuries. Items found damaged or defective must be taken out of service immediately.
And lastly, any tools or equipment exceeding eight (8) feet in length requires at least two (2) people for material handling activities. Tools or equipment exceeding eight (8) feet in length should not be transported through areas of high risk, which are restricted in nature such as narrow hallways.
Introduction to Screw and Bolt, its type and load capacities
When doing some screw and bolts tightening, have you ever wonder if you are using the correct size of screws and bolts? Are the screws and bolts you are using can withstand the stress?
Screws and Bolts are marked with specific load in tensile strength capacity in either numbers or markings on the head.
1.Grade 2 (//) screw and bolts. Made up to light duty, low carbon steel and usually between 25-30k psi (pounds per square inch) tensile strength load capacity.
2.Grade 4 (////)screw and bolts. Made up of medium duty, moderate carbon steel and has a load capacity between 42-50k psi tensile strength. It is either made using a cold rolled or forged approach of metal hardening.
3.Grade 5 (/////) screw and bolts. Made up of light heavy duty alloy carbon steel and has a load capacity of 58-70k Psi tensile strength. Its is usually made using a hot rolled and heat treated metal hardening process.
4.Grade 6-8 (////////) screw and bolts. Made up of heavy duty alloy steel (Cr-Moly)and has a load capacity of 72–180k Psi tensile strength. It is usually made using hot rolled and tempered SUS 440C / 316 for food grade for the heaviest working load capacity.
Separations of term from SCREW to BOLT start from defined ASME standard as follows: a 0 – 10 wire gauge sizes is screw, bigger than this size from 1/4” up is a bolt. For Metric, 1-5mm is screw while 6mm and up is a bolt.
Types of bolts
1.The Hexagonal head bolt. Hex-Heads are generally used for assembly where ease of tool access is sufficient such as socket, open end wrenches, or adjustable wrenches.
2.The Button head carriage bolt. Carriage bolt are used for wood and crate application. Note that head shank is made square to serve as anti-torsion lock when it is embedded in the material.
3.The Flat head slotted counter sink screws are designed for flushed head application so that surface is maintained flat. Classification can be from wood to metal sheet where location is significantly important as the counter-sink head normally locates the part in place. The counter-sink angle comes from 90° to 100° inclusive angle.
4.The Button head slotted stove bolts are good for aesthetics where smoothness of the head plays an impact on the assembly. It also use wider diameter of the head to gain more surface area.
5.The Pointed wood or metal screw (if slotted point, it is self tapping metal screw). Typical wood and metal screws are made from low carbon steel. They are driven in a pre-drilled. Holes as the size of the minor screw diameter. Self tapping or threads forming metal screws are normally with end slit to cut threads in metal.
6.The Pan Head slotted stove bolt and the Philips head stove bolt. These types of screws come in large commercial quantities as they are commonly used in general fastening applications as in toys, appliances, electrical connectors and terminals. They are normally made from low carbon steel, coated with zirconium, zinc, brass or copper where electrical conductivity is required. Some special electrical applications are made from whole material as brass, copper, beryllium or aluminum alloy.
7.The Winged nut bolt and screw are often used in applications where hand locking or tensioning is required.
8.The Stud bolt is threaded on both ends are intentionally designed to fully hold tight at one end having class “A” fit while the other end is with regular “B” or “C” fit to where the nut is fastened. The “A-fit” end is normally retained.
9.The Hex machine bolt. The significant difference of a machine screw or bolt is that the shank is smaller than the thread major diameter. These are made from medium to high tensile strength material and are used for assembly of motors, pumps and similar applications.
10.The Retainer screw. There are several designs of retainer screws, from square shank, rectangular or diamond dependent of application. The intention is to hold the specific part in place, or they rotate or move with the part.
11.The Socket head cap screw (Allen head cap screw). Socket head cap screws are commonly found in industrial machineries. The major consideration when using this type of screws includes; commonality, generally high tensile strength, miniaturization as it can serve in confine spaces for assembly and maintenance. These screws and bolts comes in heat treated, tempered, alloyed or SUS materials for food grade application.
12.The “U” Bolt. Typically designed for fastening and gripping on cylindrical parts as pipes and posts. For automotive industry, high tensile application “U” bolts are used to fasten suspension springs and engine mounts.
Rules in thread engagement on screws and bolts.
1.Minimum thread engagement must be 100% of the fastener major diameter. At best, 2x the bolt or screw diameter are essential considering softer materials / parts used in the assembly.
2.Nut engagement shall be at minimum of 1 major diameter of the fastener.
3.Where blind threaded hole is applied, a minimum of 1 major diameter clearance will be considered. This will allow room for foreign matters and trapped air to prevent rupture of the part.
4.When thread lock adhesive is applied, caution must be taken to apply only sufficient amount on the threads and not on the head. Sealant, gasket must be avoided to contaminate the fasteners, as they can go inside the threaded hole that will cause rupture.
5.Never attempt to use suspected worn threads as this will potentially create irreversible damage.
6.Use only true and certified replacement fasteners. Design engineers have carefully considered the forces and tensile strength of fasteners. Bad replacement is a mitigating safety risk.
7.Tighten the fasteners to its prescribed torque, from the designer specs and the fastener manufacturer recommendations.
Knowing your screw and bolts load capacities as well as its different type may determine the safety of your work not only to you but for others.
Screws and Bolts are marked with specific load in tensile strength capacity in either numbers or markings on the head.
1.Grade 2 (//) screw and bolts. Made up to light duty, low carbon steel and usually between 25-30k psi (pounds per square inch) tensile strength load capacity.
2.Grade 4 (////)screw and bolts. Made up of medium duty, moderate carbon steel and has a load capacity between 42-50k psi tensile strength. It is either made using a cold rolled or forged approach of metal hardening.
3.Grade 5 (/////) screw and bolts. Made up of light heavy duty alloy carbon steel and has a load capacity of 58-70k Psi tensile strength. Its is usually made using a hot rolled and heat treated metal hardening process.
4.Grade 6-8 (////////) screw and bolts. Made up of heavy duty alloy steel (Cr-Moly)and has a load capacity of 72–180k Psi tensile strength. It is usually made using hot rolled and tempered SUS 440C / 316 for food grade for the heaviest working load capacity.
Separations of term from SCREW to BOLT start from defined ASME standard as follows: a 0 – 10 wire gauge sizes is screw, bigger than this size from 1/4” up is a bolt. For Metric, 1-5mm is screw while 6mm and up is a bolt.
Types of bolts
1.The Hexagonal head bolt. Hex-Heads are generally used for assembly where ease of tool access is sufficient such as socket, open end wrenches, or adjustable wrenches.
2.The Button head carriage bolt. Carriage bolt are used for wood and crate application. Note that head shank is made square to serve as anti-torsion lock when it is embedded in the material.
3.The Flat head slotted counter sink screws are designed for flushed head application so that surface is maintained flat. Classification can be from wood to metal sheet where location is significantly important as the counter-sink head normally locates the part in place. The counter-sink angle comes from 90° to 100° inclusive angle.
4.The Button head slotted stove bolts are good for aesthetics where smoothness of the head plays an impact on the assembly. It also use wider diameter of the head to gain more surface area.
5.The Pointed wood or metal screw (if slotted point, it is self tapping metal screw). Typical wood and metal screws are made from low carbon steel. They are driven in a pre-drilled. Holes as the size of the minor screw diameter. Self tapping or threads forming metal screws are normally with end slit to cut threads in metal.
6.The Pan Head slotted stove bolt and the Philips head stove bolt. These types of screws come in large commercial quantities as they are commonly used in general fastening applications as in toys, appliances, electrical connectors and terminals. They are normally made from low carbon steel, coated with zirconium, zinc, brass or copper where electrical conductivity is required. Some special electrical applications are made from whole material as brass, copper, beryllium or aluminum alloy.
7.The Winged nut bolt and screw are often used in applications where hand locking or tensioning is required.
8.The Stud bolt is threaded on both ends are intentionally designed to fully hold tight at one end having class “A” fit while the other end is with regular “B” or “C” fit to where the nut is fastened. The “A-fit” end is normally retained.
9.The Hex machine bolt. The significant difference of a machine screw or bolt is that the shank is smaller than the thread major diameter. These are made from medium to high tensile strength material and are used for assembly of motors, pumps and similar applications.
10.The Retainer screw. There are several designs of retainer screws, from square shank, rectangular or diamond dependent of application. The intention is to hold the specific part in place, or they rotate or move with the part.
11.The Socket head cap screw (Allen head cap screw). Socket head cap screws are commonly found in industrial machineries. The major consideration when using this type of screws includes; commonality, generally high tensile strength, miniaturization as it can serve in confine spaces for assembly and maintenance. These screws and bolts comes in heat treated, tempered, alloyed or SUS materials for food grade application.
12.The “U” Bolt. Typically designed for fastening and gripping on cylindrical parts as pipes and posts. For automotive industry, high tensile application “U” bolts are used to fasten suspension springs and engine mounts.
Rules in thread engagement on screws and bolts.
1.Minimum thread engagement must be 100% of the fastener major diameter. At best, 2x the bolt or screw diameter are essential considering softer materials / parts used in the assembly.
2.Nut engagement shall be at minimum of 1 major diameter of the fastener.
3.Where blind threaded hole is applied, a minimum of 1 major diameter clearance will be considered. This will allow room for foreign matters and trapped air to prevent rupture of the part.
4.When thread lock adhesive is applied, caution must be taken to apply only sufficient amount on the threads and not on the head. Sealant, gasket must be avoided to contaminate the fasteners, as they can go inside the threaded hole that will cause rupture.
5.Never attempt to use suspected worn threads as this will potentially create irreversible damage.
6.Use only true and certified replacement fasteners. Design engineers have carefully considered the forces and tensile strength of fasteners. Bad replacement is a mitigating safety risk.
7.Tighten the fasteners to its prescribed torque, from the designer specs and the fastener manufacturer recommendations.
Knowing your screw and bolts load capacities as well as its different type may determine the safety of your work not only to you but for others.
Introduction to Screws, Bolts and Nuts
Screws, Nuts and bolts, generally called Fasteners are the basic and essential components in any mechanical assembly, machineries, and parts that hold the individual components together to its intended function and use. Critical to this application includes material of the fastener with respect to the application; load capacity in tensile strength and torque; application and environment versus corrosion; maintainability, availability and cost; and proper selection of fasteners with respect to applied design functions.
1.Material of Fastener with respect to the application. Fastener, nuts and bolts’ material must be carefully selected with respect to its intended use and application. SUS 316 grade is recommended for food-grade or corrosive environment. High tensile materials are use for high load and impact application.
2.Load holding capacity. Nuts and bolts have their respective load capacity specified by the manufacturers. This specification is very important consideration in machine design to ensure safety and integrity of a mechanical assembly. Specific letter or number code is embossed at the bolt head for user quick reference.
3.Application and environmental corrosion aspects. Harsh environment concern pertaining use of fastener is one major consideration to ensure safety and reliability of tool and products. For food grade industry, proper selection of non-toxic, non-oxidant material is often recommended and prescribed by law. SUS 316 grade is often recommended and food grade steel where appropriate is used.
4.Maintainability, availability and cost is also a consideration in selecting fasteners. Some special steel / metal materials maybe applicable but not economical to use due to cost and availability as they are not commercially manufactured.
5.Selection with respect to design functionality. Not all fasteners, screws, bolts, nuts, washers can serve the same purpose that will satisfy the intended design function. As the case, some maybe too brittle or too soft with respect to torsion, temperature, shock and impact, and load carrying capacity. For general maintenance practices, replace fasteners only the specified grade or the same as the original part that needs replacement.
The basic design of screw is from the basic knowledge of an inclined plane that has been used from the ancient time to gain mechanical advantage and transmit power. It has been furthermore developed to hold, fasten, and to apply force as a means of power transmission. Fine threads are used for fine adjustment applications while coarse or normal threads are used for fasteners and jacks.
Proper care of screws, bolts and nuts includes keeping them rust-free at all times. Maintain it soaked in light lube oil to avoid rusting. Else you live and suffer these consequences; corroded fasteners, worn-out threads, squeaky, rattling parts and assemblies, falling off machine and body parts will result to catastrophic failure and DEATH.
And lastly, screw, bolts and nuts are CHEAP! Replace immediately if it shows any sign of wear and tear, corrosion, before it creates irreversible catastrophic damage!
1.Material of Fastener with respect to the application. Fastener, nuts and bolts’ material must be carefully selected with respect to its intended use and application. SUS 316 grade is recommended for food-grade or corrosive environment. High tensile materials are use for high load and impact application.
2.Load holding capacity. Nuts and bolts have their respective load capacity specified by the manufacturers. This specification is very important consideration in machine design to ensure safety and integrity of a mechanical assembly. Specific letter or number code is embossed at the bolt head for user quick reference.
3.Application and environmental corrosion aspects. Harsh environment concern pertaining use of fastener is one major consideration to ensure safety and reliability of tool and products. For food grade industry, proper selection of non-toxic, non-oxidant material is often recommended and prescribed by law. SUS 316 grade is often recommended and food grade steel where appropriate is used.
4.Maintainability, availability and cost is also a consideration in selecting fasteners. Some special steel / metal materials maybe applicable but not economical to use due to cost and availability as they are not commercially manufactured.
5.Selection with respect to design functionality. Not all fasteners, screws, bolts, nuts, washers can serve the same purpose that will satisfy the intended design function. As the case, some maybe too brittle or too soft with respect to torsion, temperature, shock and impact, and load carrying capacity. For general maintenance practices, replace fasteners only the specified grade or the same as the original part that needs replacement.
The basic design of screw is from the basic knowledge of an inclined plane that has been used from the ancient time to gain mechanical advantage and transmit power. It has been furthermore developed to hold, fasten, and to apply force as a means of power transmission. Fine threads are used for fine adjustment applications while coarse or normal threads are used for fasteners and jacks.
Proper care of screws, bolts and nuts includes keeping them rust-free at all times. Maintain it soaked in light lube oil to avoid rusting. Else you live and suffer these consequences; corroded fasteners, worn-out threads, squeaky, rattling parts and assemblies, falling off machine and body parts will result to catastrophic failure and DEATH.
And lastly, screw, bolts and nuts are CHEAP! Replace immediately if it shows any sign of wear and tear, corrosion, before it creates irreversible catastrophic damage!
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