Buying Guide

59
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AHEAD OF THE FLOW
®
Revised 7/20/2018
Sizing NIBCO Automatic Stop Check Valves F-869-B
STEP 1
A. Calculate and chart the expected steam volume requirements for each hour
of boiler operation. See example chart on left.
B. Total the volume and divide by the number of hours the boiler is in operation
to get steam Hourly Average volume in lbs/hour.
STEP 2
Example 1 - This is a typical boiler system where the steam volume is consistent
throughout the year. Use the Sizing Chart below, left section with 2 psi pressure drop.
1. Identify system steam working gauge pressure.
For our example we will use 125 psi.
2. Use Hourly Average steam demand calculated in Step 1 above. For our
example use 26,958 from chart on left, center column.
3. Find the Gauge Pressure column in Sizing Chart below closest to the system
pressure of our example, 125 psi, for each size valve (120 psi is closest).
4. Find the lbs/hr in Sizing Chart below closest to calculated Hourly Average of
our example, 26,958 lbs/hr (23,100 is closest).
5. Read across to choose a 6” size valve.
Example 2 - This is a typical boiler system where the steam volume is higher in the win-
ter than in summer. Use the Sizing Chart below, right section with 5 psi pressure drop.
1. Identify system steam working gauge pressure.
For our example we will use 125 psi.
2. Use Hourly Average steam demand calculated in Step 1 above. For our
example use 38,667 from chart on left, right column.
3. Find the Gauge Pressure column in Sizing Chart below closest to the system
pressure of our example, 125 psi, for each size valve (120 psi is closest).
4. Find the lbs/hr in Sizing Chart below closest to calculated Hourly Average of
our example, 38,667 lbs/hr (37,400 is closest).
5. Read across to choose a 6” size valve.
NOTE: It is better for control consistency to size the automatic stop check valve on the
smaller side than on the larger side.
HOUR
EXAMPLE 1
NORMAL
VOLUME
lbs/hr
EXAMPLE 2
WINTER
VOLUME
lbs/hr
12 AM 17,000 29,000
1 13,000 24,000
2 15,000 26,000
3 13,000 25,000
4 10,000 22,000
5 14,000 25,000
6 15,000 26,000
7 20,000 31,000
8 23,000 34,000
9 39,000 50,000
10 44,000 55,000
11 45,000 63,000
12 PM 40,000 51,000
1 22,000 32,000
2 35,000 46,000
3 37,000 49,000
4 34,000 45,000
5 35,000 45,000
6 33,000 44,000
7 33,000 44,000
8 34,000 46,000
9 29,000 43,000
10 27,000 40,000
11 20,000 33,000
DAILY
TOTAL
647,000 928,000
HOURLY
AVERAGE
26,958 38,667
CALCULATED STEAM VOLUME
SYSTEM REQUIREMENTS
2 psi PRESSURE DROP for consistent steam volume
STEAM VOLUME FLOW
lbs/hr
SATURATED STEAM GAUGE PRESSURE
VALVE
SIZE
10 psi 50 psi 120 psi 250 psi
1,540 2,420 3,520 2½"
2,200 3,520 4,840 3"
3,740 5,940 8,250 11,550 4"
9,900 15,400 23,100 33,000 6"
16,500 27,500 38,500 55,000 8"
5 psi PRESSURE DROP for consistent steam volume
STEAM VOLUME FLOW
lbs/hr
SATURATED STEAM GAUGE PRESSURE
VALVE
SIZE
10 psi 50 psi 120 psi 250 psi
2,640 3,630 5,720 2½"
3,850 6,380 9,350 3"
7,150 11,000 16,500 23,100 4"
16,500 25,300 37,400 51,700 6"
29,700 46,200 66,000 93,500 8"
SIZING CHART