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32
Control Pressurestat for Booster Applica-
tion —
The standard dual pressure switch furnished with the
5F,H compressor cannot be used for booster application.
Replace it with an appropriate low temperature dual
pressurestat that can operate at values shown in Table 24. Any
commercial pressure switch is acceptable; for example,
an Allen-Bradley Bulletin 836, type L33 for R-12 or type 1
for R-22.
Table 24 — Control Pressurestats for
Low Stage Application
CHARACTERISTICS R-12
R-22, R-502, OR
R-507/404A
Switch Action — High Open on pressure rise Open on pressure rise
— Low Open on pressure fall Open on pressure fall
Range — High 20
″
Vac to 65 psig 30
″
Vac to 110 psig
— Low 30
″
Vac to 20 psig 30
″
Vac to 25 psig
Differential — High 8 to 30 psi adjust. 12 to 30 psi adjust.
— Low 5 to 15 psi adjust. 9 to 30 psi adjust.
Max Pressure — High 200 psig 300 psig
— Low 120 psig 300 psig
-100
-90
-80
-70
-60
-50
-30
-40
-20
-10
0
-100
-90
-80
-70
-60
-50
-30
-40
-20
-10
0
+50
+40
+30
+20
+10
0
-10
-20
+50
+40
+30
+20
+10
0
-10
-20
-30
-40
SATURATED DISCHARGE TEMPERATURE F
SATURATED DISCHARGE TEMPERATURE F
120
110
100
90
80
80
90
100
110
R-502 (SEE NOTE)
R-22R-22
R-12
SATURATED SUCTION TEMPERATURE F
SATURATED SUCTION TEMPERATURE F
SATURATED INTERMEDIATE TEMPERATURE F
SATURATED INTERMEDIATE TEMPERATURE F
NOTE: For R-502, lower saturated intermediate temperature is approximately 5 F.
Fig. 21 — Optimum Intermediate Temperature for 2-Stage Compression
(Incorporating Equal Compression Ratios per Stage)