Air Bag Maintenance And Storage Procedures

Air Bag Maintenance And Storage Procedures

MAINTENANCE

Since their introduction in 1970, air bags have proven invaluable not only in extrication but in heavy lifting, moving, shoring and patching situations. For air bag systems to remain in good and safe operating order, a maintenance program is mandatory.

In the past several years, air bags have become important tools for use in fire and rescue services.

To always ensure that your air bag system is in top operating condition, maintenance and safety checks should be performed at regular intervals. Although different manufacturers have a specified maintenance performance as well as a safety check on their air bag system, it’s important to remember that in the United States, test criteria is not standardized in air bag manufacturing. Each manufacturer determines its own design, minimum/maximum engineering and test specifications. Fortunately, all U.S. manufacturers use strong, quality safety factors.

To correctly perform a maintenance test, it is essential to assemble your air bag system in the following order:

• air supply
• pressure regulator (if using compressed air tanks)
• controller
• supply hoses
• air bag

Since these components are designed to work together as a system for maximum safety and efficiency, elimination of any part can cause weakness or a safety breakdown in the operations. Safety mechanisms are built into the air bag system to ensure proper venting for any sudden change or shift in loads.

Maintenance test procedure

The following is a step-by-step, high-pressure air bag system maintenance test procedure:

1. Connect the regulator to the compressed air tank. Tighten the regulator’s assembly mechanism to the tank. If a hand wheel, tighten by hand; if not, use a wrench to secure a good seal.
2. Check the hose end that runs from the regulator. Inspect for dirt and corrosion on the hose’s male fitting; to clean, use a rag or a soft wire brush. Next, check the air inlet coupling on the controller for dirt, sand and corrosion. This female coupling collects dirt and sand between the collet and barrel; to clean, use a strong source of air to suction out.
3. Hook the hose from the regulator to the controller. Pull on the hose to assure that it is securely plugged into the controller.
4. Close the control valve on the regulator (the small valve controlling air flow from the regulator to the controller). Open the air tank and adjust the air pressure to its proper setting specified by the manufacturer. Check for any leakage around the connection from the regulator to the tank. If leaking exists, tighten the hand wheels; if this does not stop the air leakage, replace the nylon seat washer. If the regulator has to be tightened with a wrench, shut off the air tank, remove the regulator, and check for burrs or nicks on the regulator seat. If they exist and there is not a replaceable seat, it will have to be filed or smooth finished.
5. Next, check low and high-pressure gages to be sure they register pressure inside the regulator. If not, lightly tap the gages, as they sometimes stick during long periods of storage or they could be damaged or broken. If gages do not operate smoothly or function properly, contact the manufacturer for replacement. If the liquid is gone in liquid-filled gages, contact the manufacturer for repair or replacement.
6. If the gages operate properly, now check for air leakage around all gages, the seat valve and the shut-off valve. Watch the low-pressure gage to determine any decrease in pressure. This will indicate a leak somewhere in the regulator.
7. Close the ball valves on the fitting controllers. If you have a dead-man controller, it will already be in the closed position. If there are no leaks in or around the air bottle and regulator, slowly open the air flow valve to charge the hose between the regulator and controller. Be sure to adjust the pressure to the manufacturer’s recommended regulator setting.

Closely check the hose for nicks, cuts or bubbles. Also, look for creases or folds that can occur during storage of the regulator and hose. Check around the pressed couplings for hose cuts. Internal hose weakness will be indicated by an outside bulge. Run your hand down the length of the regulator hose to make sure there are no bubbles or bulges. If this check is negative, go on to the next step.

8. Check for air leaks at the joints of the fitting controller. If a leak exists, mark the area with a felt tip marker for repair after the test is completed. Use liquid epoxy or Loctite to repair leaks in fitting controllers. If you have any problems or questions, consult the manufacturer. Remember, most fitting controllers have a hard drying epoxy or Teflon coating so the controller maintains its shape and will not loosen. Before opening the ball valves to allow air to flow from the relief valves, check to make sure the reliefs are closed. On fitting controllers, turn the notched handle clockwise; on dead-man units, the reliefs will close automatically.

On a fitting controller, be sure the lead seal is still attached to the top of the relief valve. If the lead seal is still missing, the unit must be returned to the manufacturer to be tested and certified. The relief is designed to vent at a predetermined pressure. CAUTION: This relief is the heart of the safety system. If it does not operate properly, the bag could either over or underinflate, causing severe safety problems. After you close both reliefs on the dual controller, hook the air lines to the controller and the air bag. Check and clean couplings on hoses and controller, if needed, as previously described.

9. Once the reliefs are closed and the hoses are connected from the controller to the bag, slowly open one ball valve. Be sure that the gage begins to register pressure. Close the ball valve at about 50 percent of maximum air pressure rating of your system. Again, check the hose from the controller for cuts, nicks and bulges. Check for ferrule or clam cuts around hose fittings. If irregularities are found, replace the hoses. On a dead-man controller, simply pull the joy stick lever toward the inflate position, watch the gage to be sure it begins to register, then release it at approximately 50 percent of the rated capacity. Perform hose check the same way.

The hoses from the air bag to the controller are manufactured to be a specific size with specific elasticity so that if an air bag is overinflated or a load shift and/or shock occurs, air will be properly relieved from the bag to the controller without causing damage to the bag or the load. If you have further questions or problems, consult the manufacturer’s operation manual or the manufacturer directly.

10. After you’ve checked the hoses, examine the air bag. Nicks, cuts and abrasions are of no major concern unless the steel or fabric cords are exposed. Remember, if you can see the steel or fabric cords, you are in the danger zone and the bag should be returned to the manufacturer for testing and evaluation. Check for air leaks at the nipple. Also check for bubbles or bulges on the surface of the bag.

If the bag is in good shape, extend the bag out to the end of the hose so the controller, hose and air bag are in a straight line. At this point, finish inflating the bag to the maximum inflation pressure—the red line on the gage. The relief valve should open at ±.05 of the red line setting. If it doesn’t, shut off the ball valve and open the regulator manually. On a fitting style, turn the notched knob counterclockwise; on a dead-man style, push the joy stick to deflate and then let it come back to neutral. By opening and closing these valves several times, the seat washer in the relief will be freed.

Relief sticking is normally caused by storing the relief valves in a tightly closed position (fitting controllers only) Dead-man controllers have a spring override that will not allow the relief to become bonded to the brass seat.

Once you’ve opened and closed the manual relief on a fitting controller, simply refill the bag with air to determine if it will relieve automatically. If it does, recheck the hoses for further bubbles, nicks, cuts or bulges. Also recheck the bag for air leaks, bulges or cuts open to the steel or fabric cords. If you have a dual controller and have completed the test for one side, repeat the test for the other side using a different hose and another air bag. All air bags should be tested in this manner for nicks, cuts and exposed steel or fabric cords.

Once you’ve finished testing all air bags and hoses, the maintenance procedure is complete.

Storage procedures

Correct storage procedures are also important factors in the maintenance of air bag systems.

1. Pressure regulator. The pressure regulator was never designed to take a lot of abuse. Store the regulator where it will be secure and not slide in the compartment, which can cause gage damage or breakage. Coil the hose loosely and smoothly and not tightly around the regulator. Before storage, check to see where the hose is fastened to the regulator so it is not stored with creases or folds. Always return your regulator to neutral (zero). This is a requirement in most states.
2. Controller. Before storing a fitting controller, always loosen the relief caps or the notched caps at the top of the relief values. Store the controller valves in the open position to prevent the washers from becoming bonded to their seats. This will extend the life of your seat washers.

A dead-man controller will automatically return to its neutral position, so it’s not necessary to adjust any of the seats. Protect the fitting controller to prevent breaking the plastic ball valve handles if jolted. Most gages are protected by a rubber or plastic bumper rail. When storing the controller, DO NOT store it where it can be hit, or where cribbing or other tools might fall on it.

3. Hoses. Keep hoses wound in a coil, belted or tied. Don’t lay heavy sharp objects on the hoses that will cut or crush the sidewall.
4. Air bags. Bags should be stored in a flat position with nipples facing the operator so that during unloading the nipple will always be in an up position. If the bags are stored standing on their edges, make sure that the nipple is either at the top left or right-hand comer; this will prevent personnel from stacking the bags in the compartment with all the weight on the nipples. The nipples can be the weakest portion of the bags, so don’t store or drag air bags on this area—even though nipples are replaceable in the field.

Cleaning care

After using air bag systems in oil, sand, dirt, sludge, etc., you need only a mild detergent mixed with warm water.

For controllers and hoses, wipe off excess dirt with a rag and scrape off grease and oil. Lay the bags flat on the floor, pour on some of the soap mixture and use a brush or broom to scrub the surface. Rinse the bags, hoses and controllers with water and let them dry. Rubber preservatives, black rubber paint, etc., should not be used on air bag surfaces. This will cause the bag to become slippery and works against the manufacturer’s safety margin for adhesion. Once the bags are dry, store them as previously discussed.