SECTION 7 – MAINTENANCE
FORM 155.32-ICOM2.EN.UL
ISSUE DATE:1/10/2018
157
JOHNSON CONTROLS
Figure 74 -
Duhring Diagram / PTX Chart (°C)
10.0
15.6
21.1
26.7
32.2
37.8
43.3
48.9
54.4
60.0
65.6
71.1
76.7
Useful Conversion
Formulas
T
o
convert °C (Centigrade) to °F (Fahrenheit) or
°F
to
°C:
°C
=
°F + 40
–
4
0
°F =
(°C
+ 40) x 1.8 – 40
1.8
1 atm (atmosphere at sea level) = 14.696 psia = 0 psig = 760 mmHg = 29.92 in
Hg
1 mm Hg = 1000 microns = 0.3937 inch Hg = .01934 psi
1 in Hg = 25.4 mm Hg = .491 psi
1 psi = 2.036 in Hg = 51.7 mm Hg = 2.31 ft H
2
O
1 ft H
2
O = .433 psi
1 lb = .4536 Kg = 453.6 gms
1 liter = .2641 U.S. gal = 1.057 U.S. quarts
1 U.S. gallon = 3.785 liters
1 inch = 25.4 mm
1 ton refrigeration (12,000 Btu/hr) = 3.52 kW
Absorption Liquid
Chillers
Duhring Diagram/PTX Chart
4.4
82.2
87.8
93.3
98.9
104.4
1
10.0
1
15.6
121.1
126.7
132.2
137.8
143.3
148.9
154.4
160.0
165.6
171.1
176.7
-1.1
4.4
10.0
15.6
21.1
26.7
32.2
37.8
43.3
48.9
54.4
60.0
65.6
71.1
76.7
82.2
87.8
93.3
98.9
104.4
0.6
0.8
1.1
1.3
2.0
4.0
5.3
6.7
8.0
9.3
10.7
12.0
13.3
20.0
26.7
40.0
53.3
66.6
80.0
93.3
106.6
120.0
132.7
2.7
SOLUTION TEMPERA
TURE °C
CR
YST
ALLIZA
TION AREA
SA
TURA
TION PRESSURE kPa
REFRIGERANT TEMPERA
TURE °C
93.3
98.9
104.4
1
10.0
1
15.6
121.1
126.7
132.2
137.8
143.3
148.9
154.4
160.0
165.6
171.1
176.7
40%
45%
50%
55%
60%
65%
40%
45%
50%
55%
60%
65%
70%
