Normally Opened Valve | NO Valve

What is a normally opened valve? Why is it called normally open? Please refer to the article below by valve sales engineers

1. What is normally open valve

Normally open valve is a valve that can close, open or regulate flow. However, in normal state, the valve is always open. The normally open characteristic of the valve also means that at the installation location the valve rarely needs to block or regulate flow.

Normally Opened Valve

Valves can be conventional types of valves but always in an open state, such as: ball valves, butterfly valves, gate valves,… or solenoid valves.

2. NO valve symbol meaning

NO stands for Normally Opened, so NO valve is a normally open valve. Normal open Valves are denoted on design drawings by a non-bold valve symbol

Normally Opened Valve

3. When to use NO valve

Normally open valve is used at locations on the pipeline with characteristics

  • The valve installation location rarely requires blocking or regulating the flow with reduced flow
  • In cases where blocking or regulating the flow is required, it is rarely used

Normally Opened Valve

4. Normally open valve type

Although NO valve can be many different types of valves. However, experts often say that it is a normally open solenoid valve to distinguish it from a normally closed valve. Because, solenoid valve is a valve with a high frequency of opening and closing.

Normally Opened Valve

5. Normally open valve voltage

Normally Open Solenoid Valve is referred to as having a variety of voltage like solenoid valves in general. Below are the types of power sources that valves commonly use

  • 220VAC
  • 24VDC
  • 12VDC

Normally Opened Valve

6. What is the difference between NC and NO valves

Normally closed and normally open solenoid valves of the same size may look identical, but the valve mounting location and internal construction are different.

  • A normally closed (NC) valve remains closed, blocking flow, until energized to open.
  • A normally open (NO) valve remains open, allowing flow, until energized to close.

Normally Opened Valve

7. Normally open valve application

The application of valves is something that only users, sales engineers or valve experts understand. Valves are used in a number of situations

  • Close the valve when a fluid change is required
  • Close the valve for mixing
  • Close the valve to allow the system to perform another task for a short time

Normally Opened Valve

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