Carrier 09RH specifications Booster R Factors, Suct Discharge Temperature F

			Table 23 — Booster “R” Factors
	SUCT				DISCHARGE TEMPERATURE (F)
	TEMP		–50	–40	–30	–20	–10	0	10	20	30
	(F)						R-12
	–80		—	1.230	1.276	1.328	1.377	1.429	1.470	—	—
	–70		—	1.186	1.230	1.280	1.330	1.380	1.421	1.458	1.489
	–60		—	—	1.183	1.233	1.284	1.334	1.375	1.410	1.441
	–50		—	—	—	1.189	1.238	1.287	1.328	1.363	1.397
	–40		—	—	—	—	1.190	1.240	1.280	1.318	1.350
	–30		—	—	—	—	—	1.291	1.234	1.270	1.307
						R-22
	–100	1.261		1.310	1.360	1.410	1.453	—	—	—	—
		1.221		1.271	1.319	1.371	1.414	—	—	—	—
	–90	1.214		1.263	1.313	1.361	1.407	1.448	—	—	—
		1.175		1.221	1.270	1.321	1.368	1.408	—	—	—
	–80	1.170		1.218	1.269	1.315	1.360	1.400	1.434	—	—
		1.129		1.172	1.221	1.271	1.319	1.359	1.394	—	—
	–70		—	1.172	1.221	1.269	1.313	1.351	1.388	1.424	—
			—	1.125	1.173	1.221	1.270	1.311	1.348	1.382	—
	–60		—	—	1.178	1.220	1.267	1.303	1.340	1.377	1.406
			—	—	1.125	1.172	1.221	1.263	1.300	1.337	1.367
	–50		—	—	—	1.175	1.219	1.256	1.291	1.329	1.360
			—	—	—	1.123	1.173	1.217	1.252	1.289	1.319
	–40		—	—	—	—	1.171	1.209	1.245	1.281	1.311
			—	—	—	—	1.126	1.169	1.205	1.241	1.261
	–30		—	—	—	—	—	1.160	1.199	1.233	1.265
			—	—	—	—	—	1.121	1.159	1.196	1.227
		Air-cooled (R-12 and R-22)						Water-cooled (R-22 only)
						[0.212 x low stage bhp]
NOTE: For R-502, “R” Factor = 1 + low stage capacity (tons)
	50
	40
	30
	20
	15
	10
OF REFRIGERATION	9
	8
	7
	6
	5				SATURATED
	4
	3					SUCTION
TONS
							TEMPERATURE
	2
									F
									-
									100
	1							-
								90
							-
							80
						-
						60
				-
				40
	0.5	10	15	20	30	40		50	60		70
	5
					SAFETY FACTOR %

Fig. 19 — Booster Compressor Selection

Safety Factors

Determining Intermediate Pressure — In applica- tion of commercial compressors to staged systems, the lowest total bhp per ton and most economical equipment selection results when using approximately equal compression ratios for each stage. It is also economical to juggle assigned compres- sion ratios to fit available sizes of machines.

	100
		MULTIPLYING FACTORS
		FOR OTHER SPEEDS
	90
RPM	80
AT 1750
	70	CAPACITY
% RATING
	60		BHP
	50
		1000	1200	1400	1600	1800

SPEED (RPM)

Fig. 20 — Multiplying Factors —

Nonstandard Speeds

The use of Fig. 21 (page 32), will allow direct determination of proper intermediate pressure that will result in equal com- pression ratios per stage for a direct 2-stage system. Informa- tion in Fig. 21 is given in terms of saturated temperature instead of pressures, for easier use with compressor ratings.

Existence of a second appreciable load, at some higher suction pressure level, will often dictate the most convenient intermediate pressure.

Gas Desuperheating — Operation of a direct staged system requires cooling of the gas between stages; otherwise, highly superheated discharge gas from low-stage machine would be taken directly into the suction of higher stage com- pressor and further compression would result in excessive heating of this compressor.

Liquid Cooling — It is also necessary to employ liquid cooling between stages and increase refrigeration effect of liquid delivered to evaporator to realize rated capacity of boost- er compressor. Amount of refrigeration expended in cooling liquid between stages is accomplished more economically at the level of high-stage compressor suction than at the level of low-stage suction.

Three common methods of gas desuperheating and liquid cooling for direct stage systems are illustrated in Fig. 18. In open-type systems, refrigerant liquid is cooled down to the saturation temperature corresponding to intermediate pressure. In closed-type systems, good intercooler design usually results in refrigerant liquid being cooled down to 10 to 20 degrees above saturation temperature corresponding to intermediate pressure.

Oil Separators and Lubrication — In cascade-type systems, where evaporators and suction lines are properly designed for oil return to the compressor, oil separators are usually not used.

In direct stage systems, however, oil may tend to accumu- late in one of the stages and thus result in lack of lubrication in other machine. By use of oil transfer lines, equalization of oil level between crankcases can be achieved by manual operation at periodic intervals. Automatic control of proper oil return to both compressors is effected by use of a high stage discharge line oil separator, returning oil to high stage machine, and a high side float, connected to high stage machine crankcase, which continually drains excess oil from this crankcase down to the next lower stage compressor (Fig. 18).

For booster application, factory oil charge should be drained and replaced with a suitable viscosity oil for low temperature application.

31