rubber strips (146) from the power plant.
(e) Shut off source of refrigerant gas and
b. Testing.
pressurize condenser with nitrogen until mixture of
(1) Pressure test evaporators.
refrigerant gas plus nitrogen reaches 100 psig. Shut off
(a) Attach adapter flange plates (see
source of nitrogen, close shutoff valve near disconnect
fitting, and separate the disconnect fitting. Use leak
detector to check for leakage from condenser through
(b) Apply compressed air at refrigerant inlet
disconnect fitting.
flange, pressurize evaporator to 148 2.0 psi gauge,
(f) Fabricate an air-tight box large enough to
and immerse in water for five minutes. There must be
contain one unit at a time. Locate hole for leak detector
no leakage indicated by complete absence of bubbles,
probe on side of air-tight box near the bottom, and seal
or evidence of permanent deformation of evaporator as
hole with tape. Use leak detector to check for residual
a result of pressure applied during test.
refrigerant gas in bottom of air-tight box. If any is
(c) Dry evaporators as thoroughly as
detected, blow out with compressed air and recheck with
possible with compressed air and complete drying by
leak detector. When no refrigerant gas remains, seal
heating in an oven for at least one hour at 250 F
charged and pressurized condenser inside air-tight box
(121.1C) maximum.
so that no refrigerant gas can escape.
(2) Test evaporator for refrigerant leakage.
(g) After 30 minutes, remove tape, insert
(a) Seal evaporator as outlined in paragraph
leak detector probe, and check for any refrigerant gas
(1) above.
that has leaked from condenser and settled to bottom of
(b) Connect refrigerant inlet to the
air-tight box. Remove condenser from box.
refrigeration system service unit (para 2-4b) as shown in
(h) If no leakage is detected during either
check, permit refrigerant gas and nitrogen to escape
(c) Open valve connecting evaporator to
from condenser.
vacuum pump-and evacuate evaporator for at least 15
minutes at maximum pressure of mercury absolute.
Note. Remove condenser from test area if there is a
(d) Shut off valve to vacuum pump and
possibility that escaping refrigerant gas may affect other test
charge evaporator to 60 5 psi with refrigerant.
in area.
(e) Shut off source of refrigerant and
pressurize evaporator with nitrogen until mixture of
(i) If leakage is detected, release refrigerant
refrigerant plus nitrogen reaches 100 psi gauge. Shut off
gas and nitrogen from condenser and replace faulty
source of nitrogen, close shutoff valve near disconnect
condenser with a known good one.
fitting, and separate disconnect fitting. Use leak detector
c. Installation.
to check for leakage from evaporator through
(1) Position the condenser (187, fig. 6-1, sheet
disconnect fitting.
6 of 6) and new tape (186) in the power plant and secure
(f) Fabricate an air-tight box large enough to
using the bolts (184), screws (182) and washers (183,
contain evaporator. Locate hole for leak detector probe
185).
on side of air-tight box near the bottom, and seal hole
with tape. Use leak detector to check for residual
Note.
Observe cleaning, inspection and repair
refrigerant in bottom of air-tight box. If gas is detected,
instructions for tube assemblies given in paragraph 6.2b.
blow out with compressed air and recheck with leak
Also, use new foam tape each time condenser is replaced.
detector. When no refrigerant remains, seal charged
and pressurized evaporator inside air-tight box so that
(2) Install the tube assemblies. 6-6.
no refrigerant can escape.
Evaporators
a. Removal.
Note.
Remove evaporator from test area if
there is a
(1) Disconnect the tube assemblies that connect
possibility that escaping refrigerant may affect other tests in
to the evaporators.
area.
(2) Remove the bolts (144, fig. 6-1, sheet 4 of
6) and washers (1451 to remove the evaporators (147)
and
6-15