Series 1250 Pneumatic Chemical Injection Pump
Operating Manual
Page 11 of 19
FIGURE 4: VOLUME FACTOR TABLE, SERIES 1250
PLUNGER DIAMETER
VOLUME FACTOR
1/8 IN
3.477
1/4 IN
0.869
3/16 IN
1.545
3/8 IN
0.386
1/2 IN
0.217
1/8 IN SHORT STROKE
0.0061
3/16 IN SHORT STROKE
0.0138
1/4 IN SHORT STROKE
0.0245
3/8 IN SHORT STROKE
0.0552
1/2 IN SHORT STROKE
0.0982
FIGURE 5: VOLUME DE-RATING PERCENTAGE VS DISCHARGE PRESSURE
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
Discharge Pressure (PSIG)
3.2.2.2 Volume per stroke decreases as the discharge pressure rises. It is necessary to apply a Volume De-Rating
Percentage (VDP) to the Unrated Stroke Rate (USR). The VDP is based on the expected discharge pressure the pump
will experience. Use the VDP Graph (Figure 5) to find the VDP, taking care to use the curve for your specific plunger
diameter:
3.2.2.3 Use the resulting VDP to calculate the Target Stroke Rate as follows:
TARGET STROKE RATE
=
[USR]
[VDP]
Vo
lu
m
e
D
e
-Ra
te
P
e
rc
e
n
ta
g
e
(
V
DP
)
0
500
1,
000
1,
500
2,
000
2,
500
3,
000
3,
500
4,
000
4,
500
5,
000
5,
500
6,
000
6,
500
7,
000
7,
500
8,
000
8,
500
9,
000
9,
500
10,
000
10,
500
11,
000
11,
500
12,
000
CP/MAN-PRD-015 REV. 15 EFF. DATE: 07/08/2022
