Seat leakage classifications

09/01/1999



Seat Leakage Classifications
(In accordance with ANSI B16.104-1976)


Leakage class designation


Maximum leakage allowable


Test medium


Test pressure


Testing procedures required for establishing rating


I


---


---


---

No test required provided user and supplier agree.


II

0.5% of rated capacity

Air or water at 50 to 125

45 to 60 psi (3.1 to 4.1 bar) or maximum operating differential whichever is lower

Pressure is applied to valve inlet, with outlet open to atmosphere or connected to a low head-loss measuring device, full normal closing thrust provided by actuator.


III

0.1% of rated capacity

As above

As above

As above


IV

0.01% of rated capacity

As above

As above

As above


V

0.0005 liters per minute of water per inch (mm) of port diameter per psi (bar) differential.

Water at 50 to 125

Maximum service pressure drop across valve plug, not to exceed ANSI body rating. 100 psi (6.9 bar) pressure drop minimum.

Pressure applied to valve inlet after filling entire body cavity and connected piping with water and stroking valve plug closed. Use net specified maximum actuator thrust, but no more, even if available during test. Allow time for leakage flow to stabilize.


VI

Not to exceed amounts shown in Class VI Seat Leakage Allowance table based on port (orifice) diameter.

Air or nitrogen at 50 to 125

50 psig (3.4 bar) or maximum rated differential pressure across valve plug, whichever is lower.

Actuator should be adjusted to operating conditions specified with full normal closing thrust applied to valve plug set. Allow time for leakage flow to stabilize and use suitable measuring devices.

Source: Control Engineering with data from Fisher Controls.



Class VI Seat Leakage Allowance


Nominal port diameter


Leak Rate

Inches

Millimeters

ml per minute

Bubbles per minute (1)

1.5

38

0.30

2

2

51

0.45

3

2.5

64

0.60

4

3

76

0.90

6

4

102

1.70

11

6

152

4.00

27

8

203

6.75

45

1. Bubbles per minute as tabulated are an easily measured suggested alternative based on a suitable calibrated measuring device such as aary from those shown, as long as they correctly indicate the flow in ml per minute.

Source: Control Engineering with data from Fisher Controls



Comments?
E-mail dharrold@cahners.com





No comments
The Engineers' Choice Awards highlight some of the best new control, instrumentation and automation products as chosen by...
The System Integrator Giants program lists the top 100 system integrators among companies listed in CFE Media's Global System Integrator Database.
The Engineering Leaders Under 40 program identifies and gives recognition to young engineers who...
This eGuide illustrates solutions, applications and benefits of machine vision systems.
Learn how to increase device reliability in harsh environments and decrease unplanned system downtime.
This eGuide contains a series of articles and videos that considers theoretical and practical; immediate needs and a look into the future.
Sensor-to-cloud interoperability; PID and digital control efficiency; Alarm management system design; Automotive industry advances
Make Big Data and Industrial Internet of Things work for you, 2017 Engineers' Choice Finalists, Avoid control design pitfalls, Managing IIoT processes
Engineering Leaders Under 40; System integration improving packaging operation; Process sensing; PID velocity; Cybersecurity and functional safety
This article collection contains several articles on the Industrial Internet of Things (IIoT) and how it is transforming manufacturing.

Find and connect with the most suitable service provider for your unique application. Start searching the Global System Integrator Database Now!

SCADA at the junction, Managing risk through maintenance, Moving at the speed of data
Flexible offshore fire protection; Big Data's impact on operations; Bridging the skills gap; Identifying security risks
The digital oilfield: Utilizing Big Data can yield big savings; Virtualization a real solution; Tracking SIS performance
click me