Refrigerant Receivers
Types:
• full size receivers - holds entire system charge (has queen valve and king valve)
• Oversized Receiver – holds excess system charge (condenser flooding)
• Partial Receiver – holds a portion of the system charge in the receiver and the rest in condenser
Components
• Inlet - Queen Valve – Full size
• Outlet – king valve – Quill - All receivers
• Liquid level indicators on large receivers (bulls eye)
• Liquid level gauge glass ( ball checks for protection if glass breaks)
Receiver Capacity As Required by B-52
• (4.6.2) most hold the entire refrigerant charge and only occupy 90% of its volume at 90 F
• if refrigerant side head pressure control is used receiver must be oversized by 50 %
Formula
- sizing of receivers Cr = Res + 20% / 0.9
cr = capacity of receiver
res = ref. charge in system (lb)
20% = extra ref. charge
• = 90% fill limit of a receiver
example Question: find the size of a receiver required for a system that has a requirement for 83 lbs of refrigerant
Cr = (83 + 20% or 83 lbs + 1.2) / 0.9 = 110.67 lbs ref.
High Pressure Safety
• purpose: a pressure responsive mechanism designed to stop the operation of the compression at predetermined safe pressure
• settings: water cooled 20% above condensing pressure
• settings: air 20% below high side design pressure
Relief Safety Devises
• purpose: a safety mechanism designed to open before dangerous pressure is reached
• usually mounted any place in the system where liquid refrigerant may be isolated by valves
Types
• fusible plug – temperature operated (non resetting)
• rupture disk – pressure operated (non resetting)
• pressure relief – valve pressure operated (resets when pressure drops to safe limit approximate. 10 to 20 % below setting
Approximate. Discharge Settings for PRV 's
• R 22 approximate 300 PSIG
• R 12 approximate 175 PSIG
Capacity of Relief devises
• the minimum required discharge capacity is found using the following formula
C = fDL
C = minimum discharge capacity lb/air/min
D = outside diam. Of vessel (ft.)
L = length of vessel
f = factor dependant on refrigerant (table 6)
Example question:
Select a PRV for the following Receiver
Receiver 36 “ diam.
Length 5 ft.
Ref. R 12
C = 1.6 x 3 ft. x 5 ft. = 24 lb/air/min
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