Flomatic DCV10 Installation Manual

Double Check Valve Installation Instructions

Models DCV 2-1/2” – 10”

Basic Installation Instructions:

CAUTION: Installation of Double Check Valves must be performed by qualified, licensed personnel.
Faulty installation could result in an improperly functioning assembly.

The installer should be sure the proper assembly has been selected for the particular installation.
Danfoss Flomatic Model DCV Double Check Valves are for use on potable water lines where a health hazard would not

exist in the event of a backflow situation.
Proper performance is dependent upon following these installation instructions and prevailing govern m ental and industry

standards and codes. Failure to do so, according to Danfoss Flomatics limited Warranty "releases Danfoss Flomatic of
any liability that it might otherwise have with respect to that assembly". Such failure could also result in an improperly
functioning assembly.

Damage to the assembly could result wherever water hammer and/or water thermal expansion could create excessive
line pressure. Where this could occur, shock arrestors and/or pressure relief valves should be installed downstream of
the assembly.

1. Before installing a Model DCV Double Check Valve, flush the lines thoroughly to remove all debris, chips and other
foreign matter. If required a strainer should be placed upstream of the Double Check Valve. CAUTION : Do not use a
strainer in seldom used emergency water lines such as fire lines.

2. Provide adequate space around the installed unit so that the testcocks will be accessible for testing and servicing.

3. Always consult local codes for installation methods, approvals and guidelines.
Outdoor Installation

Model DCV Double Check Valve may be installed outdoors only if the assembly is protected against any freezing
conditions. Exposure to freezing conditions will result in improper function or damage to the assembly. The installation

location must be kept above 32
Indoor Installation

Indoor installation is preferred in areas that are subject to freezing conditions. All the basic installation instructions apply
to such installations.

Parallel Installation
Where uninterrupted service from a single meter connection must be maintained, two or more Double Check Valves
may be connected in parallel. All the basic installation instructions apply to a parallel installation. Be sure to allow
adequate room between the units for testing and repair.

Placing the Assembly in Service
After the installation of a Model DCV unit has been completed, place the unit in service as follows:

1. Start with both shut-off valves closed. Slowly open the inlet shut-off valve until the backflow preventer is completely
pressurized.

2. After the assembly has been pressurized, vent all trapped air by slightly opening each of the four testcocks.

3. Slowly open the downstream shut-off valve. The Model DCV Double Check Valve is now in service.

4. After the backflow preventer has been properly installed, test the assembly (see Test Procedures). If the assembly
fails the test, remove the first and second check valves and thoroughly flush the assembly. Clean rubber seats of all
debris and place unit back in service.

o

F. All the basic installation instructions apply.

Danfoss Flomatic

Danfoss Flomatic Corp, 15 Pruyn’s Island, Glens Falls, New York 12801

Phone: [phone] Fax: [phone] www.flomatic.com

June 2006 Rev. B (8/08)

DCV

Double Check Valve Installation Instructions

Models DCV 2-1/2” – 10”

MAINTENANCE INSTRUCTIONS

1. GENERAL

A. Clean all parts thoroughly with water after disassembly.
B. Carefully inspect silicone discs, and o-rings for damage.
C. Test unit after reassembly for proper operation.

2. SERVICING CHECK VALVES

A. Close inlet and outlet shut-off valves.
B. Open No. 2, 3, and 4 test cocks to release pressure from valve.
C. Remove the cover bolts valve cover.
D. Remove check valve spring clip and check valve assembly.
E. Inspect check valve seat and o-ring for debris and damage.
F. To remove silicone disc, unscrew check valve stem from disc
holder.
G. Remove disc retainer and disc from the disc holder and inspect
for cuts or embedded debris.
H. The silicone disc may be inverted if the reverse side is
undamaged.
I. Inspect the valve cavity and seat area for damage and debris.
J. Reverse the above procedures to reinstall the check valve assemblies.

NOTE: Check valves can only be installed in one configuration,
they are not reversible.

TEST PROCEDURES – Refer to local codes and prevailing test methods.
Method #1 – Two-hose method

EQUIPMENT REQUIRED:
Fittings (if required) and Test Kit

Danfoss Flomatic

SPRING RETAINER

SPRING

O-RING

SEAT RING

STEM

DO NOT REMOVE THE SPRING
RETAINER FROM THE STEM
ASSEMBLY. Remove the disc
holder from the stem assembly.

DO NOT DISASSEMBLE

DISC RETAINER

DISC

DISC HOLDER

HIGH SIDE HOSE

BY PASS HOSE

HIGH SIDE BLEED

NEEDLE VALVE
(BEHIND BODY)

LOW SIDE BLEED
NEEDLE VALVE
(BEHIND BODY)

LOW SIDE HOSE

VALVES

FILTERS

BLEED TUBE

Danfoss Flomatic Corp, 15 Pruyn’s Island, Glens Falls, New York 12801

Phone: [phone] Fax: [phone] www.flomatic.com

June 2006 Rev. B (8/08)

DCV

Double Check Valve Installation Instructions

Models DCV 2-1/2” – 10”

TEST #1

PURPOSE: To determine the static pressure drop across
check valve No. 1
REQUIREMENT: The 1

st

check valve must have a

minimum of 1.0 psi in the direction of flow.

1. Flush testcocks and install fittings (if needed)

2. Make sure By-pass, High & Low Bleed valves are open

3. Attach high side hose to testcock No.2

4. Attach low side hose to testcock No.3

5. Close Shutoff Valves 1 and 2

6. Slowly open testcock No 2 then No 3

7. Close High Side Bleed

8. Close Low Side Bleed

9. Record the value of CV1 (MUST be 1.0 psi or greater)

10. Close testcocks, open Shutoff Valve #1 and remove
test equipment

Final Steps

1. Close testcocks.

2. Open shut off valve #1

3. Open shut off valve #2 slowly

4. Remove test equipment and fittings – open valve on test kit.

Method #2 – Single-hose method

EQUIPMENT REQUIRED:
Fittings (if required) and Test Kit

Note: For both of the following tests the test kit differential pressure gauge must be held at the same level as

rd

the 3

testcock (high point). Be sure that hoses not being used are also kept at this level.

TEST #2

PURPOSE: Test No.2 check flow thru the 2
REQUIREMENT: The 2

nd

check valve must have a

minimum of 1.0 psi in the direction of flow.

1. Moving fittings to testcocks 3 & 4 (if needed)

2. Make sure By-pass, High & Low Side valves are open.

3. Attach High Side hose to testcock No.3

4. Attach Low Side hose to testcock No.4

5. Close Shutoff Valve #1

6. Slowly open testcock No.3. and No. 4

7. Close High Side Bleed.

8. Close Low Side Bleed..

9. Record the value of CV2 (MUST be 1.0 psi or greater)

Danfoss Flomatic

nd

check valve.

BY PASS HOSE

HIGH SIDE HOSE

HIGH SIDE BLEED

NEEDLE VALVE
(BEHIND BODY)

LOW SIDE BLEED
NEEDLE VALVE
(BEHIND BODY)

LOW SIDE HOSE

VALVES

FILTERS

BLEED TUBE

Danfoss Flomatic Corp, 15 Pruyn’s Island, Glens Falls, New York 12801

Phone: [phone] Fax: [phone] www.flomatic.com

June 2006 Rev. B (8/08)

DCV

Double Check Valve Installation Instructions

Models DCV 2-1/2” – 10”

TEST #1

PURPOSE: Test No.1 check flow thru the 1
REQUIREMENT: The 1

st

check valve must have a

st

check valve.

minimum of 1.0 psi in the direction of flow.

1. Flush testcocks and install fittings (if needed)

2. Install sight tube on testcock #3

3. Install bleed valve on testcock #2

4. Attach high side hose to bleed valve.

5. Open testcock #2.

6. Bled air from gage by opening high side needle valve
then close.

7. Open testcock #3 to fill tube then close testcock #3.

8. Close Shutoff valve #2 (make sure center of gage is at
the level of the water in sight glass) then #1

9. Open testcock #3.

10. Gage reading = gage stabilizes and water stops
running out of testcock #3.

11. Close testcock #2 & #3

12. Open shutoff valve #1.

13. Record valve of CV1 (MUST be 1.0 psi or greater)

Final Steps

1. Close testcocks.

2. Open shut off valve #1

3. Open shut off valve #2 slowly

4. Remove test equipment and fittings – open valve on test kit.

TROUBLE SHOOTING GUIDE

Symptom Cause Solution

1. Check valve fails to

hold 1.0 PSID minimum

a. Debris on check disc sealing surface

b. Leaking gate

c. Damaged seat disc or seat o-ring

d. Damaged guide holding check open

e. Weak or broken spring

2. Chatter during flow
conditions

3. Low flow passing
through valve

a. Worn, damaged or defective guide or

undersized assembly

a. Low supply pressure

b. Gate valves not fully open

c. Installed backwards

3 Year Limited Warranty: Danfoss Flomatic valves are guaranteed against defects of materials or workmanship when used for the
services recommended. If in any recommended service, a defect develops due to material or workmanship, and the assembly is
returned, freight prepaid, to Danfoss Flomatic within 36 months from the date of purchase, it will be repaired or replaced free of
charge. Danfoss Flomatics’ liability shall be limited to our agreement to repair or replace the valve only.

TEST #2

PURPOSE: Test No.1 check flow thru the 2
REQUIREMENT: The 2

nd

check valve must have a

minimum of 1.0 psi in the direction of flow.

1. Move sight tube from testcock #3 to testcock #4

2. Move bleed valve and high side hose from testcock #2
to testcock #3 .

3. Open testcock #3.

4. Open high side bleed – bleed air from gauge

5. Close high side bleed.

6. Open testcock #4 to fill tube

7. Close testcock #4 (make sure center of gage is at the
level of the water in sight glass)

8. Close shut off valve #1

9. Open testcock #4.

10. Gage reading = gage stabilizes and water stops
running out of testcock #4.

11. Record value of CV2 (MUST be 1.0 psi or greater)

a. Disassemble and clean

b. Disassemble and clean or repair

c. Disassemble and replace

d. Disassemble and clean or repair

e. Disassemble and replace
a. Disassemble and repair or replace
guide or replace with large assembly

a. Use pressure gauge to verify pressure

b. Turn handle counterclockwise

c. Re-install with flow arrow pointing in

direction of flow

Danfoss Flomatic

nd

check valve.

Danfoss Flomatic Corp, 15 Pruyn’s Island, Glens Falls, New York 12801

Phone: [phone] Fax: [phone] www.flomatic.com

June 2006 Rev. B (8/08)

DCV