Carrier 09RH specifications Pneumatic Compensation

5H120, 5H126 CAPACITY CONTROL (Fig. 8) — This ca- pacity control system is slightly different from the system on 5F40 through 5H86 compressors. Unloaded starting and capac- ity reduction is obtained by holding open the suction valves of a number of cylinders. For capacity control purposes, a suction-pressure-actuated capacity control valve pilots a hydraulic relay that loads or unloads cylinders in pairs.

Major Difference from the 5F40 through 5H86 Capacity Control:

1.The hydraulic relay design provides a wider pressure differential between cylinder cut-in and cutout points. The relay is a small, easily removed cartridge rather than an integral part of pump end cover.

2.The surge chamber on 5H120 and 5H126 is an integral part of the bearing head casting.

PNEUMATIC COMPENSATION OF COMPRESSOR CAPACITY CONTROL — Adding a control air line to the external pneumatic control connection permits pneumatic resetting of the control point in accordance with changes in operating conditions. Each pound of change in air pressure resets the control one pound in the same direction. Thus, a one- pound rise in air pressure will cause unloading to begin at a suction pressure one pound higher than the original control point, etc. Figure 9 shows a typical pneumatic control arrange- ment. All components and installation instructions are field supplied.

PNEUMATIC CONTROLLER

OUTPUT TO INCREASE ON

DECREASE IN CONTROLLED

TEMPERATURE

CONTROL

3 TO 15 PSIAIR SIGNAL TO

COMPRESSOR

SENSING

BULB

Fig. 9 — Pneumatic Compensation