TENNEY ENVIRONMENTAL
Tenney Junior Test Chambers: Models TJR and TUJR, W942, or WF4
Page 43
Charging a Low Stage:
1. Do not charge liquid into the low stage.
2. Do not charge the system when it is below room temperature.
3. Do not use charging hoses on very high pressure refrigerants or low stage refrigerants. Cylinder
pressure exceeds 500 PSIG.
4. Never charge the unit when it is running.
As you will note from the above, low stage charging procedure differs from the conventional method. Correct
charging pressure will be noted on the equipment nameplate or in the instructions. Remember that it is
important that you charge by pressure, not by volume of refrigerant.
Use 1/4 inch copper tube between refrigerant cylinder and system. Open the cylinder valve very slowly.
Charge into the suction side while closely watching the discharge gauge. When correct pressure is reached,
shut off the refrigerant cylinder valve, allowing the system to equalize from 10 to 15 minutes. If the pressure
drops, crack open the cylinder valve, and slowly raise the pressure. Always take enough time. Systems with
expansion tanks connected by a capillary tube or restrictor valve may need several minutes for gas pressure
to equalize.
Keep the refrigerant cylinder upright when charging. Above all, be careful. Do not over-pressurize.
Disconnect the cylinder immediately when charging is complete. A leaky cylinder valve could continue to
bleed high pressure refrigerant into the system, possibly causing it to rupture. Do not take chances. The
saturation pressures of low temperature refrigerants are extremely high.
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