Azbil HLS Series - Chapter 10. Azbil Low Emission Standard-Compliant Gland Packing; Overview; Structure

10-1
Chapter 10. Azbil Low Emission standard-compliant
gland packing
10-1. Overview
Azbil low emission gland packing is a gland structure that employs a Live Load structure
to its performance for a long period of time. In order to meet the emission regulations for
Volatile Organic Compounds (VOC) required by the U.S. Clean Air Act Amendments
(CAAA), we confirmed that the amount of gland leakage was not more than 500 ppm in
terms of the atmospheric concentration of the equivalent methane value on the basis of Azbil
Corporation's own evaluation criteria. * For the structure of the gland, refer to the structural
drawing of Azbil low emission gland packing in Fig. 10-1.
* In Japan and overseas as of October, 2005, there are no industry standards that lay down any
evaluation method for gland leakage.
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
(11)
(12)
Gland stud
Gland nut
Packing ange
Spring case
Belleville spring
Packing follower
O-ring (inner diameter side)
O-ring (outer diameter side)
Gland packing
Spacer
Stem
Stung box
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
(11)
(12)
Key
Part name
Fig. 10-1. Structural drawing of Azbil low emission gland packing
10-2. Structure
The gland packing P4519 for use in Azbil low emission gland packing is woven PTFE yarn
with carbon fiber core. This gland packing provides asbestos-free properties in addition to low
sliding friction and adaptability to heat cycles, and is adaptable to a wide range of fluids.
This gland packing is fastened with a Live Load structure comprised of Belleville springs. The
Belleville springs are made to be tight compressing at the time of initial fastening. As a valve
is operated, the seal performance of the gland packing becomes deteriorated because of strain
release, but the restoring force of the Belleville springs automatically retightens it to maintain
seal performance. The Belleville springs are installed in the spring case for the purposes of
positioning and environmental protection. The loading conditions of the Belleville springs can
be determined by checking a front window and scale marks of the spring case.
The set of parts can be added to an existing product without any change of its main body or
actuator if it is an applicable control valve.