Azbil AGVB User Manual

9-2. Structure
The main packing (No. P4519) is PTFE yarn with a carbon fiber core. It features low friction
and can be used for various types of fluids. The main packing (No. P6617CL) is an expanded
graphite packing. The part of it that slides is aligned with an expanded graphite sheet that
was specially modified and lubricated. The adapter packing (No. P6720) is made by braiding
expanded graphite yarn reinforced with PTFE fiber, and features low friction.
These gland packings are tightened by the live-loaded packing system, which is composed of
Belleville springs and other parts. With other systems, in the course of valve operation, seal
performance deteriorates due to loosening of the gland packing. The force of the Belleville
springs reduces the release of tension to maintain the seal. The load on the Belleville springs
can be observed from the position of the packing flange and packing follower.
9-3. Starting Operation
Before operating the valve, tighten (or retighten) the gland.
For instructions, refer to
9-4-2"(3) Tightening".
If leakage from the gland continues even after proper tightening, obtain and prepare parts as
indicated in
"9-4-1. Preparation for assembly", and follow the procedure given in
"9-4-2. Assembly".
9-4. Assembling the Parts of the Gland
9-4-1. Preparation for assembly
(1) Checking the surface condition of the parts
Any flaw or the like on the surface of the parts may cause leakage from that area, and the
specified seal performance may not be achieved. Therefore, check the surface of the following
parts.
Table 9-1. Parts to be checked for surface condition
Part name Checkpoints Possible problems
Stem
•
No flaws or defects,
including scratches and
dents
•
No rust or corrosion
•
The entire surface is even.
•
No burrs
•
Clean surface, with no
adhering coating material,
powder, or dirt.
Any flaw, rust, corrosion, burrs, dirt, etc.,
may cause leakage from that area, and
the specified seal performance may not
be achieved.
Stuffing box
Both ends of the spacer
Packing follower
Packing contact surface
O-ring groove
Packing flange
Gland nut contact surface
Any flaw, rust, corrosion, burrs, dirt, etc.,
may cause insufficient tightening, and
the specified seal performance may not
be achieved.
Packing flange (entire
surface)
Gland stud bolt
Gland nut
•
No flaws, rust, or defects Any flaw, rust, defect, etc., may cause
control valve damage, leading to
injuries.
9-2

Azbil AGVB Specifications

General

Brand	Azbil
Model	AGVB
Category	Control Unit
Language	English