How to Measure Butterfly Valves

Butterfly valves are used in piping for not just a tight shut-off but also for high-performance t control the flow of water. Butterfly valve manufacturers ensure that these valves are made with the highest accuracy and go through multiple QC before hitting the stores. The rigid testing is to ensure that they carry distinctive features to properly control the water force and flow.

How does a butterfly valve look on the inside

A butterfly valve is a quarter-turn valve that controls fluid flow and throttling. A thin metal disc revolves around the stem. The mechanism for opening and closing allows and restricts the flow of a medium between an upstream and downstream pipe.

Measurements for a butterfly valve based on international standards

Butterfly valve standards ensure that they are perfectly crafted to cater to the necessary needs with no faults. Some of the organizations that oversee these standards are:

1. International Organization for Standardization

2. European Committee for Standardization

3. ANSI Valve Standards (United States)

4. BSI Valve Standards (United Kingdom)

5. CSA Valve Standards (Canada)

6. DIN Valve Standards (Germany)

AWWA C504 for Rubber-Seated Butterfly Valves

These are used by the American Water Works Association for potable water. This specification is for sizing AWWA rubber-seated butterfly valves. As a result, all readings and testing protocols must adhere to the specifications in this standard.

API 609 for Lug and Wafer Butterfly Valves

This standard is followed to ensure uniformity in design. It also ensures uniformity in face-to-face dimensions and materials. According to this, the range of sizes can be:

1. 2” to 12” at 200 psi gauge pressure WOG service. 

2. 14″ to 30″, rated pressure can be 150 psi gauge at WOG service. 

MSS SP-67 for General Butterfly Valves

This standard is for listing proper dimensions and designs. It is also for marking and testing. The standard sizes are NPS (nominal pipe size) 1½ to NPS 72.

UL 1091 for Safety Butterfly Valves for Fire Protection Services

The UL 1091 standard specifies the requirements for butterfly valves used in fire protection systems. If you are designing valves for this type of service, you should look into the standard’s dimension, design, installation, and testing requirements.

Defining butterfly valve dimensions

They usually range from 2 inches to 60 inches. But some are also available for up to 96 inches. Butterfly valve manufacturers ensure these specifications are mentioned along with the product. The valve size usually refers to the diameter equal to a nominal pipe. Ask the manufacturer for a catalog for the sizes so you can decide properly.

Measuring valve seat size

When you want to fix and replace a butterfly valve seat, you have to be mindful of the size. Purchasing the right seat size for your pipe is very important. Use a caliper to measure the size for accuracy.

What is the Difference Between DN/PN and NPS/Class?

There are many pressure-temperature rating standards that manufacturers mention like DIN ISO, PN10, PN16, PN25, and PN40. These are metrics used in either English or the imperial system. For instance, PSI for pressure and NPS for nominal pipe size is the terms used under the British units.