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Chapter 4. Service and unit replacement
The only component which calls for service is the pilot relay. When malfunctioning of the
pilot relay is suspected, service it as mentioned below. When the pilot relay is found to be
defective, replace it with a new one.
When the meter body is required to be modified due to specification change or application
change or due to failure, order your Azbil agent. If it is required to be modified for yourself,
order the service tools and Service Manual SM2-5220-0000 “Replacement Procedure of Meter
Bodies.”
4-1. To replace the pilot relay
Remove the pilot relay by removing the three screws shown in Fig. 4-1
If the gasket has been deteriorated or damaged, replace it also when replacing the pilot relay.
To install the pilot relay, place the gasket in the correct position, set the pilot relay on the
manifold by setting the guide pin at the bottom of the pilot relay to the guide hole, and tighten
the screws evenly.
4-2. To service the pilot relay
Remove the pilot relay as described in 4-1 above, service it as described below, and then install
it in the original position.
(a) Remove the three assembly screws (1) and nuts (19). (See Fig. 4-1)
(b) Parts (3) to (17) will separate in order. It is not necessary to separate parts (2) to (6) unless
they are to be replaced.
(c) Clean metal parts with approved solvent such as petroleum naphtha or Clorothene.
Depress the valve stem (2) against the conical spring (5) to allow the solvent to penetrate
through the seat which is hit by the port section of the valve stem.
(d) Examine the inner exhaust ring (13) and value stem (2). If dirty, clean them wit a cloth.
Do not use any solvent to clean them.
(e) Dry all parts thoroughly with clean compressed air.
(f) Replace diaphragms (16) and (11) if worn or damaged.
(g) Reassemble the pilot relay by rejoining all parts in order with assembly screws (1), and
nuts (19). Tighten the screws evenly.
