Chapter 7 – Maintenance
TestEquity 1016H & 1027H Temperature/Humidity Chamber
Page 7-15
Refrigeration System Charging Instructions
!
WARNING:
Repair of the refrigeration system must be performed only by a properly
trained mechanic who is experienced in repairing cascade refrigeration
systems. Do NOT substitute any component. Do NOT substitute refrigerants.
Improper repairs will void the warranty.
These instructions are intended as guidelines for repairing TestEquity chambers. Details such as
how to attach a gauge manifold are not covered. These are NOT do-it-yourself instructions!
High-Stage Charge
TestEquity does NOT recommend charging the system by relying on a clear sight glass only.
Although a clear sight glass generally means the system is fully charged, it can be misleading.
The proper charging procedure is as follows:
1.
Repair any leaks before recharging.
2.
Attach a vacuum pump and manifold gauge to the suction and discharge ports.
3.
Evacuate the system to at least 100 microns. DO NOT GUESS! You must use a micron
gauge.
4.
Use a charging scale to weigh in the type and amount of refrigerant as indicated on the
model/serial number label in the back of the chamber.
5.
Verify the cooling performance as outlined in “How to verify the chamber performance”.
NOTE: If the F4 Controller is cycling (Cool Light cycles on/off), the sightglass may appear 1/2
to 2/3 full. This is normal.
R-508B Low-Stage Charge
1.
Repair any leaks before recharging.
2.
Attach a vacuum pump and manifold gauge to the suction, discharge, and expansion tank
ports. Attaching to the expansion tank is very important because it is otherwise very difficult
to evacuate the tank through the pressure regulator or capillary tube that is connects it to the
system.
3.
Evacuate the system to at least 100 microns. Do NOT guess! You must use a micron gauge.
4.
Do NOT put any additives in the system. Pentane is NOT necessary or desirable.
5.
Charge the system until the standby pressure is 10 PSIG higher than the amount shown on
the model/serial number label in the back of the chamber. Allow time for the charge to
equalize as read on the suction and discharge gauges. The standby pressure should be
rechecked after 24 hours to make sure it is the correct pressure as shown on the label. This is
because the refrigerant mixes with the POE oil in the compressor, causing a lower standby
pressure than was initially observed. Do not mistake this initial loss of pressure with a leak.
After verifying that there is no leak, you may need to top-off the charge if the pressure is too
low.
6.
Verify the cooling performance as outlined in “How to verify the chamber performance”.
