8. Bleed the high side.
• Slowly open bleed valve (red) on top of housing and
close again when air discharge has stopped.
9. Bleed the low side.
• Slowly open bleed valve (blue) on the top of the
housing.
10. After the differential pressure gauge reaches the upper
part of the scale, close bleed valve (blue).
11. Observe the pressure drop on the differential pressure
gauge.
If the discharge valve opens the inlet check valve is
faulty and has to be replaced before further testing
Maintenance backflow preventer!
12. Slowly open needle valve (red) on backside of housing
for a quarter turn maximum.
13. Slowly open needle valve (blue) on backside of housing
for a quarter turn maximum.
14. Observe the gauge on the differential pressure gauge.
• Differential pressure drop slowly to the discharge valve
opening point.
15. Discharge valve opens and drips.
Respective opening pressure must be consulted from
the operation instructions of the installed backflow
preventer!
Discharge valve doesn't open
valves (red and blue) on backside of housing
continue with chapter 7.1.1!
16. Close needle valves (red and blue) on backside of
housing
continue with chapter 7.2.
7.1.1. Shutoff valve B could be faulty.
1. Slowly open and close shutoff valve B again.
2. Repeat steps 11 to 15 chapter 7.1.
If the discharge valve still doesn't open
valve B is faulty
has to be replaced before further
checks!
7.2. Testing outlet check valve
1. Connect hose (yellow) to the connection of needle valve
(yellow) on the back of the housing and sewage the open
end of the hose to a discharge.
2. Slowly open needle valve (red) on the back of the
housing.
3. Slowly open needle valve (yellow) on the back of the
housing.
• Hose (yellow) is deaerated.
4. Close needle valve (yellow) on the back of the housing.
5. Connect hose (yellow) to ball valve P3.
6. Slowly open ball valve P3.
7. Slowly open bleed valve (blue) on the top of the housing.
GB
8. After the differential pressure gauge reaches the upper
9. Slowly open needle valve (yellow) on the back of the
10. Observe the gauge on the differential pressure gauge.
7.3. Testing inlet check valve
1. Connect hose (red) between ball valve P1 and needle
2. Connect hose (blue) between ball valve P2 and needle
3. Close all needle and bleed valves.
4. Open ball valves P1 and P2.
5. Bleed the high side.
6. Bleed the low side.
close both needle
7. After the differential pressure gauge reaches the upper
8. Observe the pressure drop on the differential pressure
9. Slowly open needle valve (blue). Differential pressure
shutoff
10. Close needle valve (blue).
11. Open shutoff valves on inlet and outlet. Close ball valves.
6
part of the scale, close bleed valve (blue).
housing.
• Differential pressure doesn't drop to discharge valve
opening point. If discharge valve doesn't open testing is
(successfully) finished.
If the discharge valve opens the check valve has to be
replaced before further testing
flow preventer!
valve (red) on the back of the housing.
valve (blue) on the back of the housing.
• If possible sewage the bleed tube to a discharge or use
a vent surge tank.
• Slowly open bleed valve (red) on top of housing and
close again when air discharge has stopped.
• Slowly open bleed valve (blue) on the top of the
housing.
part of the scale, close bleed valve (blue).
gauge.
rises until inlet check valve begins to open.
The discharge valve mustn't drain otherwise it is leaky
and has to be replaced.
The differential pressure has to stay constant other-
wise the inlet check valve is leaky and has to be
replaced.
Clean and dry thoroughly pressure-test kit!
Let opened all needle valves and bleed valves during
storage!
Do not put pressure-test kit damp inside carrying case!
Maintenance back-
MU1H-1227GE23 R0321