4
TABLE 3
Maximum Theoretical Life (MTL) in scf at various inlet
pressure dew points and pressures.
Inlet dew point
(saturated air)
temperature
°F (°C)
Inlet Pressure psig (kgf/cm
2
)
20
(1.4)
40
(2.8)
60
(4.2)
80
(5.6)
100
(7.0)
150
(10.5)
200
(14.1)
40 (4)
50 (10)
60 (16)
6,798
4,644
3,230
10,716
7,321
5,091
14,634
9,998
6,953
18,552
12,675
8,814
22,470
15,352
10,676
32,265
22,044
15,330
42,060
28,736
19,984
70 (21)
80 (27)
2,281
1,634
3,596
2,575
4,911
3,517
6,226
4,458
7,541
5,400
10,828
7,754
14,116
10,108
90 (32)
100 (38)
1,186
872
1,869
1,375
2,552
1,876
3,236
2,380
3,919
2,883
5,627
4,140
7,336
5,397
4.0 MAINTENANCE
THE PURIFIER IS A PRESSURE CONTAINING
DEVICE. DEPRESSURIZE BEFORE SERVICING.
A. Periodically drain the two (2) vessels.
1. Filter - Before liquid level reaches cartridge bottom
cap.
2. Convertor - Each time cartridge is replaced or when
purifier is taken out of operation.
4.1 Procedure for Filter Element Replacement
(See Section 5 for cartridge replacement procedure.)
A. Filter - When pressure drop across the filter exceeds
10 psi, or when pressure drop across the purifier exceeds
15 psi.
1. The filter is supplied with a differential pressure
gauge. Pressure differential in excess of 10 psi
(0.7 kgf/cm
2
) - pressure indicator in red area -
indicates that the element should be replaced.
B. Convertor - When upper indicator band changes from
green to yellow.
C. Determine Cartridge life
1. Determine cartridge life at actual operating
conditions. At 80°F saturated inlet compressed air
temperature and 100 psig inlet pressure, a cartridge
will purify 5400 standard cubic feet of air.
2. Determine cartridge life at other conditions as
follows:
Step 1 - From Table 3, find Maximum Theoretical Life
(MTL) in standard cubic feet (scf) that model 1901 can
handle at the pressure and dew point temperature at
the inlet to the purifier.
Step 2 - If the inlet air is less than 100% saturated
(dew point temperature is less than sensible
temperature), adjust MTL for level of saturation.
Refer to Table 4 and find the Saturated Air Correction
Factor (SACF) at the intersection of the dew point
and sensible temperatures corresponding to your
operating conditions.
Step 3 - Multiply MTL from step 1 by SACF to get
adjusted MTL.
Step 4 - To find actual life in minutes, divide adjusted
life found in Step 3 by flow requirements of
breathing apparatus.
EXAMPLE
- Determine cartridge life at the following
conditions:
Flow requirement: 5 scfm
Inlet pressure: 100 psig
Inlet sensible temperature: 80°F
Inlet dew point temperature: 40°F
Step 1
- Find MTL from Table 3 at 40°F and 100 psig.
MTL = 22,470 scf.
Step 2
- Find SACF from Table 4 for 40°F dew point and
80°F sensible temperatures. SACF = 0.28
Step 3
- Find adjusted MTL by multiplying MTL by SACF.
22,470 x 0.28 = 6292
Step 4
- Find cartridge life in minutes by dividing
adjusted MTL from Step 3 by flow requirement, 5 scfm.
6292÷5 =1258 minutes (21 hours)
TABLE 4
Saturated Air Correction Factor (SACF)
Dew point (saturated air) temperatur
e
120°F (49°C)
1.00
110°F (43°C)
1.00
0.90
100°F (38°C)
1.00
0.90
0.78
90°F (32°C)
1.00
0.90
0.75
0.56
80°F (27°C)
1.00
0.88
0.70
0.51
0.39
70°F (21°C)
1.00
0.88
0.70
0.51
0.36
0.28
60°F (16°C)
1.00
0.88
0.69
0.50
0.34
0.25
0.21
50°F (10°C)
1.00
0.85
0.65
0.45
0.30
0.22
0.19
0.19
40°F (4°C)
1.00
0.87
0.65
0.42
0.28
0.19
0.15
0.13
0.13
40°F
(4°C)
50°F
(10°C)
60°F
(16°C)
70°F
(21°C)
80°F
(27°C)
90°F
(32°C)
100°F
(38°C)
110°F
(43°C)
120°F
(49°C)
Sensible temperature