How do I choose an air valve?

What are the different types of air valves? How to find the right valve for your application? Can air valves be installed underground? Are there air release valves for sewer systems? In this article you will find the answers to these and other questions.

Hawle provides several classes of air valves for different industry and flow applications. These air valves can be classified based on various factors, like function or body construction.

Based on the functions they perform on the pipeline, there are three types of Air valves:

• Air relief valves
  Air relief- or air release valves prevent air from accumulating and getting trapped in the system. They vent the accumulated air in the system to the atmosphere.
   
• Air/vacuum valves
  Air admittance valves provide air to keep a vacuum from forming in the pipeline system. They admit air into the system to counter the negative pressure causing the vacuum.
   
• Combination air valves
  A combination valve performs the function of both the air and the vacuum valve. It is designed to both admit and release air as the situation requires.

We can also classify air valves using their body construction or the number of orifices (opening). Based on this classification, there are two types:

Single Orifice Valves:
Single orifice valves have one air inlet and outlet. They find applications in venting small quantities of accumulated air out of the pipe during operation. Hawle single orifice air valves are available in models 9837 and 9838.
 

Double Orifice Valves:
Double orifice valves have one large outlet and one small outlet. The large outlet admits air in large quantities while a pipe section is being drained. It's also responsible for venting out the air during the pipe filling operation. The small outlet is responsible for venting out small amounts of accumulated air during the pipeline’s operation.

When selecting air valves for water distribution or sewage systems, there are several factors to consider. Before you even look into the manufacturer's catalog, you have to decide your system's requirements and plan. Hawle offers air valves for a wide variety of water distribution and sewage systems. To properly select one from the catalog, you have to determine the following characteristics:

Size
The opening size refers to the nominal diameter of the air valve. It affects how much air the valve is going to be able to admit or vent out. Hawle recommends following the guidelines from DVGW “Arbeitsblatt W 334” for sizing air valves.

Fluid medium
The fluid medium in the pipe is the first thing to consider when selecting an air valve. Hawle makes valves for two main types of liquids- Potable water and wastewater. It's essential to get the proper valve for each.

Operating pressure
The operating pressure (Nominal pressure) refers to the range of working pressures the valve can withstand. Although Hawle's valves have a reasonable safety factor, the valve must still match the operating conditions in the pipe. Hawle manufactures air valves in various diameters and in a wide pressure range. For example, a Hawle automatic combination air valve with triple function is available in DN 50 - DN 300 and up to PN 40 on request.
 

Connection method
When choosing a valve, you have to consider how it will interface with the pipeline infrastructure. Hawle air valves come with threaded, flanged, and BAIO connections.

Installation location
An air valve can be placed underground, above ground, or in a chamber. If the pipeline is underground, you will need to pair the air valve with an air release set for proper venting.