Lowflow Mark 6800HP Series High Pressure Regulating Valve User Manual download pdf (Page 2)

several times. This fully strokes the valve to insure

satisfactory operation.

4. With the outlet shutoff valve open, slowly screw

down the adjusting screw until the desired pressure

is shown on the outlet pressure gauge.

5. To change the controlled pressure, turn the ad-

justing screw clockwise to increase the pressure,

counter-clockwise to decrease pressure.

Warning: Never substitute a longer length adjusting

screw. Personal injury and/or damage to the valve may

result.

Maintenance

Caution: Make certain that there is no pressure in the

valve before loosening any ﬁttings or joints. The follow-

ing steps are recommended:

1. Close the inlet shutoff valve.

2. Allow pressure to bleed off through the downstream

piping. Do not attempt to reverse the ﬂow through

the valve by bleeding pressure from the upstream

side of the valve.

3. When the pressure gauges indicate that all pressure

has been removed from the system, close the outlet

shutoff valve, and the valve may be serviced.

Valve Disassembly

1. Load the range spring by turning adjusting screw

(28) clockwise at least ﬁve full turns. This will help

prevent damaging the seat during disassembly.

2. Remove the bottom cap (1).

3. Remove the trim subassembly and the return spring

(3) from the bottom cap (1).

4. Remove the o-ring (5) and the back-up rings (4)

from the bottom cap (1).

5. Unthread the seat retainer (8) from the guide (2).

Remove the o-ring (14).

6. For valves with balanced trim, remove the o-ring (35)

and back-up rings (36) from the guide.

7. Remove the retaining ring (7) from the stem (12) and

disassemble the stem and seat (10) from the seat

retainer (8).

8. Unload the range spring by turning the adjusting

screw (28) counter-clockwise.

9. Remove the eight socket head cap screws (24) and

remove the spring housing (13).

10. Remove the upper spring guide (26), the range

spring (25), the lower spring guide (23) and the ball

bearing (22).

11. Remove the cylinder (18) from the body (6) and

remove the piston (19) from the cylinder.

12. Remove the o-rings (20 & 17) and the back-up

rings (16 & 21) from the piston (19) and cylinder

(18).

13. Remove the oriﬁce (11) from the body (6). Remove

the o-ring (15) from the oriﬁce.

Valve Assembly

1. Lubricate and place o-ring (15) into the groove on

the oriﬁce (33) being careful not to cut o-ring on

threads.

2. Apply Loctite No. 242 to threads and install oriﬁce

(11) into body. Torque to 25 ft-lbs.

3. Lubricate and place o-ring (17) with two back-up

rings (16) into the groove on the piston (19).

4. Lubricate and place o-ring (20) with two back-up

rings (21) into groove on the cylinder (18).

5. Insert the piston (19) through the chambered side

of the cylinder (18) just enough to compress the

o-ring on the piston. The end of the piston with the

o-ring should go into the cylinder ﬁrst.

6. Install the cylinder (18) into the body (6).

7. Drop the ball (22) into the piston (19).

8. Install the lower spring guide (23) (into the piston

(19)). Push the piston into the cylinder until the

lower spring guide seats against the cylinder.

9. Place the range spring (25) onto the lower spring

guide (23).

10. Place the upper spring guide (26) onto the range

spring (25).

11. Install the spring housing (13) onto the body with

eight socket head cap screws (24). The spring

housing should pilot squarely onto the cylinder.

Torque the screws to 32 ft-lbs. See torque se-

quence diagram under Torquing Procedures.

12. Thread the hex jam nut (27) onto the adjusting

screw (28).

13. Place the shims onto the adjusting screw (28) and

thread it into the spring housing (13) until it makes

contact with the upper spring guide (inside the

spring housing). Use the same shims that were

originally installed on the valve. Do not alter the

thickness or the valve may fail to operate properly.

14. Thread the adjusting screw (28) into the spring

housing (13) until it just makes contact with the up-

per spring guide (inside the spring housing).

15. Load the range spring by turning the adjusting

screw clockwise ﬁve full turns. This step is impor-

tant in preventing damage to the seat while install-

ing the bottom cap and trim in the next section.

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Lowflow Mark 6800HP Series High Pressure Regulating Valve User Manual Page 2

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