Basic Lift Procedures Using High-Pressure Air Bags
FEATURES
TRAINING
During the past 15 years, the air bag has become an important tool in the equipment arsenals of fire departments, emergency medical service units, and hazardous material response teams across the country. Inflated by any available air source, an air bag can pry, spread, bend, move, or lift a car, truck, tanker, train car, even aircraft in seconds.
But, as is true with any valuable tool, the air bag can only perform at peak efficiency when used properly. And this involves theoretical as well as practical training. This article will cover step-by-step procedures for several types of basic lifts using high-pressure air bags.
Before beginning any drill, and, indeed, after every emergency response, check that all equipment is in good working order. Include other hand and power tqols in your air bag drills to learn how various equipment can work together to facilitate and expedite a rescue/extrication operation.
Just a safety reminder: Make sure that all personnel involved in a training drill are wearing full protective clothing, including gloves, helmets, and eye protection. Also, when working in a squatted position beside a vehicle, rescue personnel should maintain their weight on the balls of their feet. In case of sudden vehicle movement, this is the fastest escape position.
Let’s begin with a vehicle sitting upright on its wheels. Before beginning any vehicle rescue/extrication operation, we must first secure the vehicle. This prevents the vehicle from moving and possibly increasing the seriousness of the emergency. Position wheel chocks in both the front and back of one wheel. Chocks can also be positioned in the back of one rear wheel and in the front of one front wheel.
THE BASIC ONE-BAG LIFT (raising any one side of the vehicle)
In addition to the initial chocking, always secure or brace the opposite side of the vehicle to be lifted with 2″ x 4″ or 4″ x 4″ cribbing. For example, before lifting the vehicle’s driver’s side, build two crib stacks for placement on the passenger side. Position one stack behind the front wheel and one in front of the rear wheel. As we begin to lift the vehicle’s driver’s side, the passenger’s side will remain in a stable position.
The hollow cribbing stacks should be built at the side of the vehicle and to reach the same height as the vehicle’s frame. Have two rescuers stand with their backs to the wheelwells. Extending arms down, they will gently pull the wheelwells upward, while two other rescuers slide the crib stacks underneath the vehicle. The vehicle has to be raised approximately one to two inches. This relieves stress of the vehicle’s body weight on the springs.
On the vehicle’s lifting side, another member of the team should build a hollow-core crib stack under the frame section to be lifted. Place one solid layer of cribbing on top. Position the air bag flat on top of the stack so that the bag is within one inch of the vehicle’s frame. Be sure that the bag is centered directly under the vehicle’s lifting point. Do not arbitrarily shove the bag to any position and do not position it partially under the vehicle.
Once the bag is properly positioned:
- Attach the air bag system regulator to any compressed air source (SCBA tank, etc.).
- Turn the regulator’s low-pressure gauge to approximately 150 psi discharge pressure.
- Attach the feed hose from the regulator to the air bag system controller. All connections should be tightened by hand.
- Open the compressed air discharge valve to permit air flow to the regulator.
- Connect the air hoses from the controller’s coupling discharge to the air bag. If using a deadman controller, you don’t have to adjust the reliefs. For a fitting style controller (which should always be stored with the reliefs open), close the reliefs snuggly, not tightly, in preparation for the evolution.
- When all controller preparations are completed and all hoses secured (check this by tugging on the connections), open the petcock valve on the regulator and you’re ready to begin the air bag evolution.
Start by inflating the air bag. Notice how the bag pushes the vehicle down solidly on the opposite side cribbing and makes a complete lift. Continue inflation until the air bag fills or reaches its desired lifting point.
This doesn’t mean that you’ll have to inflate until the reliefs vent off. Locate the air pressure gauge inside the deadman control cabinet or on the fitting regulator. Notice that when the air pressure rises above the red line on the gauge, excess air automatically vents to the atmosphere. Also pay attention to the point at which the bag ceases to expand. If an air bag is capable of lifting 10.5 inches and the lift is attained at a level between 25 and 50 psi, there is no sense in continuing to inflate the bag to a full 116 or 118 psi because it will not provide additional lift. This is a method of conserving your air supply.
It’s a good idea to overinflate the bag until air vents through the relief on the controller to train operators to recognize the popping sound on the fitting controller and the hissing noise on the deadman controller.
Once the vehicle is lifted, build another crib stack to solidly support the raised vehicle, especially if you need to work on or enter the vehicle. It is extremely important that the vehicle be supported by something other than the air bag, as an air bag is a pneumatic shock arrester and will not prevent the vehicle from bouncing and swaying. Place the cribbing well out of the victim’s way.
Once you’ve completed the onebag lift procedure, pull out the secondary support cribbing, deflate the air bag, and remove all primary support cribbing.
To deflate the bags on a fitting controller, open the red or black cap on top of the relief. As you do so, you’ll hear the sound of air escaping, slowly at first and then faster as you continue. Using a deadman controller, simply activate the lever or button to deflate and the air will be disbursed out of the air bag system.
THE TWO-BAG LIFT
(raising any one side of the vehicle)
For the two-bag lift evolution, the larger air bag is always on the bottom and the smaller air bag centered on top. Center both bags underneath the load. As you face the load, one air line should enter the air bag from the left and one from the right to prevent the hoses from tangling. Supply hoses for multibag lifts should be of different colors. This will aid in the efficiency of the operation by simplifying communication and coordination. For example, assume that a yellow hose is attached to the larger bottom bag and a green hose to the top bag. Position the controller operator where he cannot see the two air bags.
Instruct him to inflate the bottom bag first (yellow hose) until the bag ceases to expand. Then, instruct him to inflate the second bag (green hose) slowly up to the desired position. Remember, in a rescue operation, you only need to achieve enough space to extricate the trapped victim or permit a medic adequate space to administer care.
When performing a two-bag lift, always inflate the bottom (larger) bag first, then the smaller, top bag. Continue to build crib stacks to support the load as it is being lifted. Never place any part of your body underneath a lifted object. If cribbing has to be pushed under the load, use a 2″ x 4″ or another tool. If the vehicle should shift or fall, body parts can quickly be crushed.
When the operation is completed, always deflate the top bag first, then the bottom bag. Remove all cribbing from under the vehicle as outlined previously in the one-bag lift.
THE TWO-BAG LIFT WITH BAGS ON OPPOSITE SIDES OF VEHICLE (raising the front end of a vehicle)
For this operation, two separate air bags will be positioned on each side of the vehicle. Keep the wheels chocked properly. Build two crib stacks as high as possible to reach the vehicle’s frame, and place one stack in front of each rear wheel assembly. Use shims to firmly stuff them underneath the frame.
Now, build two additional crib stacks and position one behind each front wheel. Place one air bag on top of each front cribbing stack. Center each air bag/stack under the vehicle to within two inches of the frame.
REMEMBER: The top row of cribbing must be solid.
Position the control operator in front of the vehicle. The goal is to obtain a smooth, level lift, shifting the vehicle’s weight slowly and evenly upward. This means the operator will have to learn the techniques of using a controller properly, particularly if two different sized air bags are being used. By maintaining consistent air flow pressure through the dual controller, the lift will be smooth and level.
For demonstration purposes, let’s say that the green hose is going to the passenger side and is connected to a 14-inch lifting bag and the yellow hose going to the driver’s side is connected to a 10.5inch bag. During the lift procedure, the bag on the passenger’s side will expand to a higher position than the bag that is on the driver’s side.
The controller must draw an imaginary sight line for himself from headlight to headlight to determine if the vehicle is rising slowly and evenly. As he sees the passenger’s side rising higher than the driver’s side, he should reduce the amount of air flow into the higher bag while continuing to fill the bag on the driver’s side until the load is balanced.
Once the smaller bag (driver’s side) has reached desired expansion height, the operator should temporarily stop the operation. An additional cribbing stack must be firmly positioned to reach the lifted point under the vehicle frame. If additional height is needed, deflate the two air bags, build the crib stack higher, reposition the bags on top of the stack, and continue the lift.
Once the operation is accomplished, secondary cribbing is removed, the air bags deflated, and the primary cribbing pulled out. Lower the vehicle to normal position.
In-line reliefs
This is a good time to review the use of the in-line relief valves. Inline reliefs permit the operator to use one dual controller to operate more than two bags during a rescue operation. The in-line relief features a safety valve, a coupling to receive the hose from the air bag, and a shutoff valve with a coupling to connect it to the controller.
One in-line relief is plugged into each discharge port on the dual controller. On the in-line relief’s front side, an air hose is hooked, connecting the in-line relief to the air bag.
Now repeat the two air bag evolution with four air bags, two bags/cribbing stack centered underneath the vehicle’s lifting point on the passenger side behind the front tire and two bags/cribbing stack on the driver’s side behind the front tire.
Now run a green hose from the bottom bag on the passenger side and a yellow hose from the bottom bag on the driver’s side. Hook these hoses into the in-line reliefs. Run another green hose from the top bag on the driver’s side and another yeUow hose from the top bag on the passenger’s side. Thus, we have one yellow and one green hose on each side of the vehicle. You’ll need two additional hoses for the in-line reliefs later in the operation, keep them handy.
Beginning with the bottom bags, open the valves on the in-line relief. Then open the air flow valves on the dual controller. It’s possible to inflate the bags one at a time or both together. Lift the vehicle evenly. As soon as the vehicle attains the desired lift point, shut off the dual controller, and then shut the in-line reliefs.
Disconnect the in-line reliefs from the controller and connect the two additional air hoses directly to the controller. Now, very carefully, continue to lift the vehicle with the other two bags. As you can see, we are performing two two-bag lifts independently of each other with only one dual controller.
IMPORTANT: Connect the inline relief to the hose, not to the air bag. And never stack more than two bags high at any time during any type of lift operation.
As an air bag inflates, it shrinks in size and its square shape is reduced. If the in-line relief had to be attached to the air bag each time we needed to re-hook or disconnect the hoses, it would be necessary to place arms and hands underneath the lifted load. For safety’s sake, keep the in-line relief on the operating end of the hose so you can maintain a minimum distance of 20 feet away from a lifted vehicle.
When lifting with two different size air bags, the vehicle can become wobbly. This is why additional crib stacks are positioned at other locations to provide support to the now lifted vehicle. The controller operator must practice the proper procedures for opening and closing valves and constantly keep an eye on the “line” between the headlights to prevent the vehicle from tipping.
Many departments hook the inline relief directly to the air bag. They think this saves the cost of two additional hoses. This is incorrect and unsafe because it puts the operator too close to the lifting evolution. The hoses are the least expensive part and the largest safety factor on an air bag system.
Another important safety precaution that’s worth repeating is that personnel should never be underneath the load during the lifting, bending, or prying operations. If you maintain this safety principle, injuries to rescuers on the scene will be drastically reduced.
AIR BAG STORAGE SUGGESTIONS
When all evolutions have been completed, the air bags are ready for storage. Check for oil, transmission fluid, or any type of petroleum based products on the bag. If it is soiled or stained, the bag should be scrubbed with a brush and mild detergent in warm water.
You should always store the bags with the nipple pointed upward, not rubbing against a shelf or sitting in the base of the cabinet. Coil the hoses. Disconnect the deadman cabinet. Release all pressure from the regulator after shutting down the compressed air supply, and be sure that no air remains either in the feed hose or in the regulator. Do not store the regulator with the hose tightly wrapped around it because this will cause kinks, cracks, or chaffing in the hose line.
