Constant Pressure Expansion Valve And Refrigerant Charge 12. Constant Pressure Expansion Valve And Refrigerant Charge; [A] Specifications [A] Specifications; [B] Function [B] Function; [C] Construction [C] Construction - Hoshizaki HNC-120AE-L Service Manual

8) Refrigerant Leak Check 8) Refrigerant Leak Check
Refrigerant leaks can be detected by charging the unit with a little refrigerant, raising the Refrigerant leaks can be detected by charging the unit with a little refrigerant, raising the
pressure with nitrogen and using an electric detector. Do not use air or oxygen instead of pressure with nitrogen and using an electric detector. Do not use air or oxygen instead of
nitrogen for this purpose, or rise in pressure as well as in temperature may cause R134a to nitrogen for this purpose, or rise in pressure as well as in temperature may cause R134a to
suddenly react with oxygen and explode. Be sure to use nitrogen to prevent explosion. suddenly react with oxygen and explode. Be sure to use nitrogen to prevent explosion.
12. CONSTANT PRESSURE EXPANSION VALVE AND REFRIGERANT 12. CONSTANT PRESSURE EXPANSION VALVE AND REFRIGERANT
CHARGE CHARGE
[a] SPECIFICATIONS [a] SPECIFICATIONS
Model: Model:
Manufacturer: Manufacturer:
Part Number: Part Number:
Refrigerant: Refrigerant:
Adjustment Range: Adjustment Range:
Pressure Rise by Adjusting Screw: Pressure Rise by Adjusting Screw:
[b] FUNCTION [b] FUNCTION
When the low side pressure drops, the Constant Pressure Expansion Valve opens and lets When the low side pressure drops, the Constant Pressure Expansion Valve opens and lets
the refrigerant flow to keep a constant pressure. the refrigerant flow to keep a constant pressure.
[c] CONSTRUCTION [c] CONSTRUCTION
Close Close
DOWN DOWN
Low Pressure Low Pressure
Adjusting Adjusting
Screw Screw
Cap Cap
Open Open
UP UP
Adjusting Adjusting
Spring Spring
Fig. 7 Fig. 7
HYP-2-5QHD-1 (HNC-120/150/180) HYP-2-5QHD-1 (HNC-120/150/180)
HYP-2-5QHD-5 (HNC-210) HYP-2-5QHD-5 (HNC-210)
Fuji Koki Fuji Koki
447283-01 (HNC-120/150/180) 447283-01 (HNC-120/150/180)
447283-04 (HNC-210) 447283-04 (HNC-210)
R134a R134a
0.01 - 0.3MPa 0.01 - 0.3MPa
0.039 - 0.049MPa / turn 0.039 - 0.049MPa / turn
IN (High Pressure) IN (High Pressure)
Needle Valve Needle Valve
Working Working
Bar Bar
Diaphragm Diaphragm
22 22
OUT (Low Pressure) OUT (Low Pressure)
Inner Spring Inner Spring
74NL5870112 74NL5870112