SERVICE AND OPERATIONAL INSTRUCTIONS

Much of this information has been discussed for the Model SC-5 transfer unit and need not be repeated; however, where we note a difference, we will discuss it.

After you uncrate and inspect the unit, make certain that the crosshead clears the packing nut. To do this, turn the master gear attached to the crankshaft. The mechanism must work freely.

Fill the crankcase with a standard grade of SAE #20 motor oil. CAUTION: Do not use any oil or grease in the cylinders or in any of the adapters or hose connections used to convey carbon dioxide. (Since this precaution was not specifically stated in the instructions for the adapters connected to the SC-5 pumping unit, we are not implying that oil or grease can be used in the adapters of Model SC-5.) In any case, follow the manufacturer's instructions. Do not add to or subtract from anything in the manufacturer's manual. Obviously, however, where the Naval Air Systems Command (NAVAIRSYS-COM) directives are concerned, they will take precedence over the manufacturer's instructions. Walter Kidde instructions direct you to use a 10-inch wrench to tighten all hose-connecting joints. While tightening the hose, you should be careful not to twist them.

A strainer and strainer adapter are inserted into the inlet line (at the supply cylinder) to the pump. They prevent any dirt or metal filings that may accumulate in the supply cylinder from blowing over into the pump and impairing the action of the valves. Knowledge of the function of the strainer is important to you when you analyze the cause of malfunctioning pump valves or other associated parts.

MAINTENANCE

The normal maintenance on this pump is limited to proper lubrication. Figure 3-7 shows

Figure 3-7.\Lubrication points.

the different lubrication points for the Walter Kidde Model 4211 transfer pump. We also recommend you drain the oil in the crankcase after every 150 hours of operation. The crankcase holds 1 pint of SAE #20 lubricating oil.

CAUTION

Do not introduce oil or grease into the compressor assembly or into the adapters or hose connections used to transfer the carbon dioxide.

Troubleshooting

Table 3-1 is from the operating manual for the Walter Kidde unit. It lists possible troubles that may occur during the operation of the carbon die-tide transfer unit, their probable cause, and indicated remedy.

Plunger Packing

Vapor leaks at the plunger packing are sometimes impossible to overcome. An invisible

Table 3-1.\Troubles that may occur during the operation of the carbon dioxide transfer unit, their probable cause, and indicated remedy

vapor leak will not affect the performance of the pump; no particular effort need be made to eliminate a leak unless it reaches the point at which it becomes visible. If a leak should develop at the lower end of the plunger, tighten the plunger guide, shown in figure 3-8, with a rod (approximately 3/8 inch by 6 inches). Do not bind the plunger by tightening it too snugly. When you can no longer adjust the tightness of the plunger guide, remove the compressor body from the frame and insert new packing as follows:

1. Unscrew the four bolts that hold the compressor body to the crosshead guide and remove the pin that holds the plunger to the crosshead.

Figure 3-8.\Compressor assembly of the Walter Kidde CO₂ transfer unit.

2. Place the compressor body in a vise and remove the plunger guide and old packing. Insert only the two large pieces of packing and the spacer. Then insert the plunger guide and turn it down as far as possible to compress and form the packing around the plunger. This operation will cause the plunger to bind, but you can free it by turning and working the plunger up and down a few times.

3. Remove the plunger guide and insert the small ring of the packing. Install the packing so that the level fits the packing already in place and the plunger guide. Replace the plunger guide and turn it in until the maximum dimension between the body at point (A) and the end of the plunger guide (B) (figure 3-8) is 1 3/16 inches. If the plunger guide is not screwed in sufficiently, the crosshead will strike the plunger guide. To free the plunger, work it back and forth several times.

4. Replace the compressor body and extend the plunger so that it can be lined up with the crosshead and the pin being replaced. After you connect the end of the plunger with the crosshead, which may have had to be moved to its top position to accomplish the connection, tighten the bolts securely. Turn the master gear several revolutions by hand to make sure the crosshead does not strike the plunger guide.