Refrigeration System - Scotsman TDE470 Service Manual

TDE470

Refrigeration System

This ice machine uses R-134a as the refrigerant.
This refrigerant has no chlorine, and therefore
requires polyolester type refrigerant oil. This oil
requires specific service procedures.
General Service
A HFC type liquid line drier is required. "Standard"
driers may not take out enough moisture and may
affect the oil additives.
The time that the refrigeration system is open to
the air must not exceed 15 minutes. The oil will
rapidly absorb moisture from the air, and the
contact time must be kept to a minimum.
A special or very sensitive electronic leak detector
will be needed to locate refrigerant leaks. Many
are on the market that will sense R-134a.
The access valves must be in the closed position
before the hose caps are removed. Do not remove
the hose caps before checking the position of the
valve. Use a 3/16" allen wrench to open and close
the valve.
Torque Stem
to 6-8 ft. lb.
Access Valve
As with any other refrigerant, do not place
pressurized air or oxygen into the refrigeration
system.
Note: The refrigeration system uses an HFC
type refrigerant and MUST use an HFC type
drier.
Evacuation to 200 microns is recommended.
Stem Cap
Torque to 8-12 ft. lb.
Fitting Cap
Torque to 7-12 ft. lb.
February 1995
Page 28
Temperature Pressure Chart, Selected Points
0
Temperature in F.
-10
-6
-4
-2
0
1
2
3
4
5
10
12
14
16
18
20
25
30
31
32
33
34
35
40
45
50
75
90
110
120
130
150
PSIG of R-134a
2.0
3.7
4.6
5.5
6.5
7.0
7.5
8.0
8.6
9.1
12.0
13.2
14.4
15.7
17.1
18.4
22.1
26.1
26.9
27.8
28.6
29.5
30.4
35.0
40.0
45.4
78.7
104.3
146.4
171.1
198.7
262.8