Dresser Masoneilan 173 Series Manual - Page 11

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4.5.3 Actuator disassembly

Release the spring compression by turning the adjustment

screw counter-clockwise, counting and noting the number

of turns in order to restore calibration after reassembly.

Remove the spring housing (9) by loosening the nuts (21). It

is not necessary to remove the housings of the 220 and 360

actuators. Remove the spring.

- For Group 1 regulators: unscrew the nut (11) and remove

the diaphragm with the diaphragm plate (6) and spring

guide (19) - (see Fig. 9).

- For Group 2 regulators: unscrew the lock nut (11) and nut

(29); remove the double diaphragm assembly with ring (30),

intermediate plate (31), diaphragm plate (6) and spring

guide (19) - (see Fig. 10).

4.5.4 Body disassembly

Unscrew and remove the cover with relevant gasket. Unscrew

the seat with a screwdriver (see Fig. 9-10)

Pull the plug off its guide and remove it from the body.

Fig.11

Example of installation layout - Group 1 regulators: 173-50

Single Diaphragm.

Fig. 12

Example of installation layout – Group 2 regulators: 173-50

Double Diaphragm.

Instructions

EY0173 – 10/08

173 Series

Self-Operating Pressure Regulators

4.5.5 Parts inspection (Figs. 9-10)

All the components are now ready to be inspected. Replace

any worn items. Clean all parts.

Pay particular attention to the condition of the disc of the plug

(24), both elastomeric and metal, and the seat.

If the seat is worn, it may be able to restore it by lapping

using a metal disc and abrasive paste.

The diaphragm should be replaced if it shows any damage.

The same applies to Teflon diaphragm protector (if

equipped).

Gaskets should not be re-used.

If preferred, the regulator may be returned to an authorized

Masoneilan repair center to be reconditioned.

4.5.6 Reassembly

Carry out the disassembly operations in reverse order. Push

the stem of the plug into its guide and tighten the seat (26).

Screw back the cover (1). Install the diaphragm/s (see 4.5)

taking care to properly arrange the Teflon protectors. Make

sure the seats of the O-rings are perfectly clean before

mounting them. Assemble:

- for Group 1 regulators: plug assembly, diaphragm plate,

diaphragm and spring guide (with gaskets), nut.

- for Group 2 regulators: plug assembly, diaphragm plate,

lower diaphragm, intermediate plate and actuator ring,

upper diaphragm, spring guide (with gaskets), nut and lock

nut.

Match the holes of the diaphragm/s with the holes in the

actuator flange and install the spring, spring holder and

housing. Turn the adjustment screw the number of turns

noted down during dismounting. Exact calibration must then

be checked when the regulator is placed back into service.

4.5.7 Replacing the diaphragm

The diaphragm may require replacement without having

to make other repairs. If the regulator is easy to access

and isolate, it can be replaced while leaving the regulator

installed in the piping provided it can be isolated. In this case,

isolate the regulator and vent all pressure. Ensure isolation

valves are locked to prevent accidental pressurization will

working on the regulator. Remove the actuator following the

instructions in section 4.5.2.

Replace and install the diaphragm and reassemble

the actuator as shown in section 4.5, 4.5.3 and 4.5.6.

Check calibration once more when the regulator is returned

to service.

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