Infloor 31075, 31076, 31077 User Manual

Code A B C D E
1” FNPT
1” MNPT
3
13/16
2
1/16
” 6
31076
1” FNPT
1” SWT
2
2
” 6
1
FNPT
1
” MNPT
3
2
” 7
E B D E B D
E B D E B D E B D
Differential Pressure By-Pass Valve
Code A B C D E
(lb)

31075

3/4” MNPT
3/4” MNPT
2
” 1

31075-31077 series

BS EN ISO 9001:2000
Cert. n∞ FM 21654
UNI EN ISO 9001:2000
Cert. n∞ 0003

01007/09 NA

Function

The differential pressure by-pass valve is used in systems with a fixed speed circulating pump supplying several zones controlled by two way zone valves. This valve ensures that the head pressure of the pump is proportional to the number of two way valves being closed. It will bypass the differential pressure created by the pump as the zone valves close, thus eliminating water hammer noise.
31077
Product range
Part # 31075 Adjustable differential pressure by-pass valve with graduated scale, flow up to 9 gpm Size 3/4" Sweat x 3/4" Sweat outlet Part # 31076 Adjustable differential pressure by-pass valve with graduated scale, flow up to 40 gpm Size 1” Female NPT x 1” sweat outlet Part # 31077 Adjustable differential pressure by-pass valve with graduated scale, flow up to 45 gpm Size 1 1/4” Female NPT+1 1/4” sweat outlet
Technical specifications Materials
Body: brass Valve plug: brass Valve plug gasket: O-R ing
seals: Union seals: asbestos free NBR Control knob: Spring: stainless steel

Dimensions

519
502A
519
599A
2 3 4 5
mH2O 6
1
A
C
3/4” SWT 3/4” SWT 2
2 3 4 5
1/4 1/8
” 2
31075
1
mH2O 6
A
7/8 1/2
” 5

Performance

Medium: water, glycol solutions
EPDM EPDM
ABS
C
Weight
9/16
” 1
Max percentage of glycol: 30% Temperature range: 32–230°F (0–110°C) Maximum working pressure: 150 psi (10 bar) Flow rates: 3/4” flow up to 9 gpm
1” flow up to 40 gpm
1 1/4” flow up to 45 gpm
Setting range: 1 - 6 m w.g. (2 - 10 psi)
519
600A
519
700A
1 2
3 4 5
mH2O 6
A
31077 1
C
1/4 1/4
FNPT
519
4 5
1/4
1
1/4
” SWT 3” 2
609A
1 2 3
mH2O 6
A
C
13/16 15/16
519
709A
4 5
1/16 11/16 11/16
” 7
1 2 3
mH2O 6
A C
Weight
5/8 3/8 3/8
” 1.5
TOT
AL
LOAD
P
A
RTIAL LOAD

Operating principle

When the spring (1) compression is adjusted using the control knob (2), the force balance acting on the valve plug (3) changes, thus modifying the threshold pressure value of the valve. The valve plug opens, activating the by-pass circuit, only when it is subjected to a differential pressure sufficient to generate a thrust greater than the thrust exerted by the spring. This allows the flow discharge through the outlet (4), limiting the difference in pressure between the two points in the system where the valve is fitted.
2
5
1
3

System operation

The job of the differential pressure by-pass valve is to maintain the pump operating point as close as possible to its nominal value (point A on the graph shown below). If the by-pass valve is not used, when the flow rate in the circuit decreases due to partial closure of the two­way zone valves, the head loss in the circuit increases, point B. The by-pass valve, set to the nominal head value of the pump, limits the increase in pressure, by-passing the flow rate G. This behavior is guaranteed at any closing condition of the system two-way zone valves. In fact, once the posit i on of the valve control knob has been established, the threshold pressure value is more or less constant as the discharge flow rate varies (see hydraulic characteristic diagrams). A proper valve sizing must guarantee a sufficient flow rate by-pass to keep the pump at its nominal operating point in all system operating conditions, for example when the first zone valves are closed.
p
p
NOMINA L
Circuit resistance curve with two-way valves partially open
B
p constant on the circuit
Pump curve
A
Circuit resistance curve with two-way valves fully open
50%
G
100%
Flow rate G

Setting

To regulate the valve, turn the knob to the required value on the graduated scale: the values correspond to the differential pressure in psi or meters w.g. to open the by-pass.
For a quick setup adjustment of the differential pressure by-pass valve, use the following manual method. As an example, a hydronic system with several zone valves: the system must be operating, the zone valves must be fully open and the by-pass valve must be set to the maximum value (a) (clockwise). Gradually open the differential pressure by-pass valve using the control knob (counterclockwise). Use a thermometer, or simply your hand, to check that the hot water is flowing into the by-pass circuit (b). As soon as a rise in the temperature is noted, turn control knob (clockwise) one half turn closed so hot water stops flowing into the by-pass (c). Lock the knob in this position (d) with the locking screw.
4
a) b)
Two-way
1 1 2 2 3 3 4 4 5 5
mH2O 6 mH2O 6
3 3 4 4 5 5
mH2O 6 mH2O 6
1 2

c) d)

1 2 3 4 5
mH2O
6
1 2 3 4 5
mH2O 6
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