5
6.1.1. Accessing the Main Valve Assembly
To access the Main Valve Assembly (MVA):
i.
Remove the securing M3 grub screw (26) from the regulator body (22).
ii.
Unscrew the M3 button screw (27) and remove the name plate (4) from the hand
wheel (5).
iii.
Unscrew the locknut (2) using a 24mm socket and remove the hand wheel (5)
from the adjusting screw (8).
iv.
With the regulator secured up-right in a vice, remove the bonnet (10) by using a
torque wrench or equivalent with 47mm open end.
v.
Un-screw and lift the top works from the assembly, inclusive of the bonnet (10),
load spring (9) and adjusting mechanism (6, 7, 8, 30).
vi.
The sensor assembly can be removed from the body by using pliers or mole grips
against the flats of the spring rest (11).
vii.
Use a 17mm open ended spanner to locate vertically over the seat nut (21), then
use an adjustable spanner to grip the 17mm spanner and loosen the seat nut (21)
until removed.
viii.
The connector pin (20) can be removed after taking the wire retaining clip (19)
from the seat nut (21).
ix.
Remove the soft seat (18), main valve (17) and main valve spring (16) from the
regulator body (22). It may be required to turn the body over and tap the base to
remove these parts.
NOTE: Cv 0.1 and Cv 0.3 models will contain a 9x1mm o-ring (not shown) below
the soft seat.
x.
Inspect the main valve (17) and soft seat (18) for damage and replace as
required.
6.1.2. Accessing the Vent Seat
It is recommended that the vent seat is only accessed in the event of failure or suspected
failure. This is often noticed as a leak to atmosphere whilst controlling downstream
pressure.
IMPORTANT: Due to its compression securing method, the vent seat will require replacing if
removed from the sensor. Ensure that all required parts are available prior to removal.
i.
To access the vent seat (13), secure the spring rest (11) in a vice and unscrew the
sensor (14) using a slotted screwdriver. Alternatively, a steel rule (or equivalent)
may be secured in a vice and used to accommodate the slot in the sensor (14).
ii.
A 17mm open ended spanner or adjustable can then be used to remove the
spring rest (11).
iii.
Remove the sensor (14) from the sensor holder (15).
iv.
Remove all o-rings (1, 3, 23, 24) from the sensor assembly and replace as
required.
v.
The vent seat (13) can be removed from the sensor using a 4mm drift punch. To
do so, secure the sensor (14) with the slotted side up and place the drift in the
4mm bore. Then lightly tap until the vent is released.
vi.
The o-ring (25) and vent seat (14) can then be replaced.
