Fisher: Maintaining life force of shop, service equipment

Air is amazing. All living things depend on oxygen to live and breathe.

Air also enables airplanes, helicopters, birds and insects to fly. And did you know air is a good conductor of sound? Without air, we cannot hear sounds.

Air is also the life force of your shop and service equipment. It is essential to have a supply of clean, dry air to provide energy to your impact wrenches and strength to carry a tire's load.

When your shop air system and pneumatic tools are neglected and air is restricted, it's the same as strangling or suffocating a person. All the strength is sapped from the system, air lines go limp, pneumatic tools weaken and eventually die and — as we all know — tires run flat and perish, too.

The good news, though, is there are things you can do to ensure that your air system and tools are and remain in peak condition to provide optimum performance.

The fall is a good time of the year to inspect your air system and impact wrenches. You've come through a busy summer servicing your commercial fleet accounts and your air system most likely has gotten a thorough workout.

Now is the time to tend to it to prevent your tire shop or service area from shutting down and your pneumatic tools from getting starved for air and losing power.

You should scrutinize three areas: the compressor, air lines and air tools. You should start in the compressor room by first determining the last time your compressor received a preventive-maintenance inspection.

If you have a piston compressor, take the following steps now:

• Change the oil. Before you begin to drain the compressor, turn it on for a few minutes to warm and thin the viscosity of the oil so that it leaves the system easily and remove the fill cap to allow air into the system. Then remove the drain plug and drain the oil;

• Replace the air inlet filter;

• Check the belt for proper tension, cracks and other signs of excess wear. Replace if necessary;

• Check the inlet and discharge valves of the pump to see if they are sticking due to carbon deposits; and

• Check the piston, cylinders, rings and valves. If they are worn, the compressor will deliver less air and will blow oil past the rings into the compressed air. If you find excessive air passing through the crankcase breather, this is an indication of worn piston rings. If you find the compressor output has dropped and/or oil in the air, put rebuilding your compressor on your things-to-do list. Manufacturers recommend that these compressors get rebuilt every 5,000 to 10,000 hours.

If you have a rotary compressor, do the following:

• Change the oil;

• Change the oil filter;

• Change the air/oil separator;

• Check the belt for proper tension, cracks and other signs of excess wear. Replace if necessary;

• Look for mechanical seal leakage; and

• Inspect the inlet valve for wear and excessive bearing play.

Manufacturers recommend that rotary compressors get rebuilt every 50,000-100,000 hours.

If you have a dryer on your compressor, which I hope you do, perform a little maintenance on it, too:

• Check to see if the condenser is clogged since this condition is the cause for air dryer problems;

• Clean the fins with compressed air or a bristle brush, but be sure not to damage the fins of the heat exchanger during cleaning; and

• The drain function at the separator should be checked regularly by monitoring the amount of discharge it puts out. (Approximately six gallons of water should be discharged from a 100 cfm dryer on an average day.)

Every air dryer drain should be serviced or rebuilt at least once a year.

Next, do a walk-around inspection of your air system. Walk from your compressor room through your shop and listen for leaks.

It's best if you can do this after hours when things are quiet and you can hear air leaks better. Check the piping and lines from the compressor all the way to your air tools.

This is really important since studies have found that on average 35% of all compressed air is lost to leaks. Replace leaking fittings, nipples, couplers and hoses immediately with the proper piping and fittings. Your compressor can be choked if the wrong ones are used.

Don't just crank up the compressor to try to get more air out of it. This will just make the air leak out faster and actually will reduce your system capacity even further. Hoses should be connected securely by installing appropriately sized quick-change chucks.

If you are hard of hearing, I suggest you buy an ultrasonic leak detection device, which is relatively inexpensive and is usually a good investment since air leaks will force the compressor to work harder and can rob the system of power to air tools. This situation could result in wheel losses when wheel fasteners can't be tightened to the proper torque.

Next check the air lines to the impact wrenches or other air tools you have. Having too much or too little air supplying the wrench is bad. The wrench becomes either hyper or anemic.

Operating wrenches with too much air pressure causes O-rings and valves to deteriorate rapidly. Usually the throttle valve is the first component affected.

This valve is either steel or plastic and is linked to the trigger to control the flow of air through the wrench. High pressure causes this valve to wear at a much faster rate.

Operating an impact wrench with too little air under-powers the tool. It will not have enough energy to operate in its torque range and you'll end up with loose wheels.

The air system must deliver 90 psi at the impact-wrench inlet with the tool running. You can check this pressure by installing a dial pressure gauge in a T fitting at the air inlet of an impact wrench and attach the hose to the other end of the T fitting. Measure the air flow to and through the impact wrench while it is running.

This test rig also can be used to detect restricted air lines or couplings that starve tools of air. If air lines are run over by vehicles or just fatigued, they can collapse internally and restrict air flow.

A 90 psi running pressure is needed at the gun since that is the recommended operating pressure of most impact wrenches. Disregard static pressure. When the tool has stopped, the air pressure in the line may be substantially higher.

If your shop has multiple tools and lifts using compressed air, you may want to consider installing air-system alarms to alert technicians when the line air pressure drops below the minimum needed for proper tool running pressures.

Impact wrenches need clean air to operate. Dust, corrosive fumes and excessive moisture can wreck an impact wrench.

In fact, moisture is their leading cause of death. If moisture enters the cylinder assembly, rust, corrosion and pitting will attack the cylinder, rotor, vanes, and end plates, which are located in the motor housing.

These parts depend on a clean and dry source of compressed air, and since there are no seals or gaskets between the cylinder and end plates, the surfaces must be clean and smooth in order to maintain torque output.

Therefore, you should have moisture separators and filters installed at every drop, which should be drained daily. If you are in a humid climate, even if you have an air dryer on your compressor, they may still need to be drained daily.

Make sure that the lines that lead directly to air tools have a filter to strain out dirt and debris, a pressure regulator to control the air to the tool and a lubricator to ensure the air tool's components are oiled as it works. (Never use air lines containing air tool lubricant for tire inflation.) Ensure all of these components are working properly. Replace them if they aren't.

Now that you've inspected the compressor and airlines, check your impact wrenches. They should be checked running in both directions on a regularly scheduled basis to ensure their output is correct. This can be done in three ways.

1. You can check torque output by installing a wheel nut on a vehicle with the impact wrench. The wrench should impact for a short duration. Most manufacturers recommend 5 seconds, but check with your manufacturer for its recommendation. Measure the torque on the nut using a torque wrench in the tightening direction.

If the working range torque is not achieved, the impact wrench will need to be inspected and may need to be rebuilt.

2. Use a Skidmore-Wilhelm gauge to measure impact wrench performance. This tool is pricey but well worth the investment if you have a lot of impact wrenches in your company. If the working range torque is not achieved, the impact wrench should be inspected and may need to be rebuilt.

3. Send the impact wrench out to a service center to check torque and bring the tool back to its original performance capacity.

If you install whip hoses on your impact wrenches, do not use Teflon tape since it can flake loose and lock up the motor. Use a liquid pipe sealant instead to prevent damage to the housing.

Couplers should not be used at the air inlet of the impact wrench where they increase overall bulk, put unnecessary strain on the inlet threads and deteriorate rapidly due to vibration. Instead, use the recommended air hose and coupling assembly shown in the manufacturer's parts list.

Since you are standing in your empty and quiet service area right now with everyone gone, look around and see where your impact wrenches are.

Are they lying around where the technicians dropped them before they clocked out? If so, it's a sure bet you're not getting optimum performance and life from them.

While impact wrenches are not precision tools, they still can deliver a reasonable torque range if treated well and maintained correctly that will reduce the amount of work you'll have to do with a precision torque wrench.

When impact wrenches are not in use, such as at night, they should be cleaned, lubricated and stored in an area where they will not collect dirt or moisture.

It is recommended that a liberal amount of air tool oil be poured in the inlet and that the tool be run before storing it.

However, follow the manufacturer's parts list for the amount and type of lubricant needed and add only the amount specified. If the impact wrench has a sealed oil lubricated clutch, it will lose power if overfilled.

Do not use air tool oil with detergent since the detergent causes the vanes or rotor blades to hang and become pitted. It also eats through the throttle valve and other small parts. The use of oil with detergent is the second most common cause of shortened impact wrench life.

When things are busy in your service area again, watch your technicians and how they work with their air tools. Impact wrenches should never be dropped, thrown, dragged around by the hose or left where they can be run over.

Use protective covers to reduce damage to impact wrenches that tend to be abused and accidentally dropped. In other words, put them on all of your impact wrenches.

Now that you've inspected your shop air system and tools, don't forget all the compressors, air lines and impact wrenches you have on your service trucks.

When was the last time they were inspected and maintained? Now is probably a good time to give them a checkup, too, to ensure their life force is in peak condition.

Peggy Fisher is president of TireStamp inc. and is based in Troy, Mich.