Technical2026-08-02
Air release valve placement should follow the pipeline elevation profile, the sections that can become isolated, and the way the system fills and drains. Mark where air must escape during filling, where trapped air may collect during irrigation, and where air must enter during shutdown. Then select and size the appropriate device for each duty.
This guide develops a placement worksheet for farm mainlines, submains, and drip blocks. It focuses on locations and operating cases, rather than repeating general valve selection or solenoid operation. Use it alongside the drip irrigation design guidelines, with the final locations and capacities checked against the selected equipment and hydraulic design.
Air moves in different directions at different times. Filling displaces air from a pipe; pressurized operation may require accumulated air to escape; draining may require air to enter. A device chosen for only one duty should not be assumed to provide the others. Rivulis distinguishes these functions in its air valve and vacuum-breaker overview.
During initial pipeline charging, automated pump controls open pilot-operated hydraulic master valves slowly to allow continuous air venting before reaching design pressure.
| Operating case | Air-management duty | Function to verify |
|---|---|---|
| Pipeline filling | Discharge displaced air | Air-discharge capacity for the intended filling conditions |
| Normal pressurized irrigation | Release accumulated air | Continuous or automatic release at the operating pressure |
| Shutdown or controlled draining | Admit air as water leaves | Air-intake capacity for the relevant draining or vacuum condition |
A combination valve can provide more than one function, but the name is not its performance curve. For a proposed assembly, record which functions are required and which its documentation confirms. This prevents a small automatic release device from being treated as an adequate large-volume air inlet simply because both products are called air valves.
A plan view shows where a pipe crosses the farm; a profile shows how its elevation changes. Add local crests, changes in slope, branches, ends, and drain outlets. Include pumping, filtration, metering, and control stations so that the air-management review follows the actual network rather than only the field boundary.
Rivulis’s location guide considers the source, system head, distribution network, and field control valves. Use these areas as prompts for a survey. Their presence does not replace an assessment of the operating duty at the specific connection.
Mark which isolation and check valves can separate one section from another. Trace an uninterrupted path from each proposed air valve to the pipe it is intended to protect, for each relevant operating state. An air valve that is connected during irrigation may be disconnected from a draining block after the field valve closes.
A long pipe can contain several local crests even when its overall route slopes downhill. Walk the installed route or use verified survey data. A modest rise over a road crossing may matter even though it is not the highest point on the farm. Label each candidate so the drawing, photograph, and equipment schedule refer to the same place.
Field pipeline profile maps specify air valve locations along high-density PE distribution lines at every localized crest and abrupt slope transition.
For a meter on a raised pipe section, Utah State University Extension recommends a continuous-acting vent to release trapped air during operation. This is a specific reason to mark elevated metering sections on the profile.
BERMAD’s guidance on automatic air valves identifies high points where air collects, including pumping, control, and filtration stations. That establishes a reason to inspect those locations; it does not justify placing the same valve size at every crest.
At each candidate, ask separate questions: can air reach this connection while the pipe operates, and can the device serve the required filling or draining duty? Record any uncertain profile section for survey. A fixed spacing rule cannot resolve an unknown local crest, a closed isolation boundary, or a different drain-out route.
Consider an illustrative hillside block supplied through a field control valve. The supply main reaches a crest before that valve. The block submain rises again after it, then feeds laterals descending toward lower beds. These are three review points, not a prescription to install three identical valves.
Oregon State University’s drip irrigation guide places vacuum relief between the solenoid valve and drip tape to limit soil suction into emitters at shutdown. Check that the proposed air path remains connected to that downstream section.
| Point | Question while irrigating | Question after the field valve closes |
|---|---|---|
| AP-1: supply-side crest | Does accumulated air have a suitable release path? | What happens to this supply section under the approved stop sequence? |
| AP-2: block-side high point | Can displaced or accumulated air reach the proposed device? | Can the isolated block admit air through a suitable connection? |
| AP-3: lower lateral group | Which branches share the same hydraulic connection? | Where does water leave, and which higher sections can be affected? |
The key finding may be that a supply-side vent cannot provide an air path to the block through a closed field valve. Moving or adding a device requires a design review of the block-side connection and capacity. It is not enough to count the air valves installed anywhere on the property.
Repeat the sketch for a different normal valve combination. A maintenance isolation, a bypass position, or a changed sector schedule may alter which sections communicate. Keep those permitted operating states with the drawing so that later operators understand the intended protection boundaries.
Rivulis explains that soil ingestion during shutdown can occur when water drains from low emitters and pressure falls below atmospheric in higher parts of the line. Suitable air admission addresses that mechanism. It does not mean that stored water must remain inside every lateral.
Separate two objectives in the design brief: limiting harmful sub-atmospheric conditions and reducing unwanted water discharge at low points. They may require different components and operating decisions. Use our drip irrigation drain-out guide for the second objective. A wetter low bed after shutdown is an observation to investigate, not proof that the air valve has failed.
For buried laterals, document how the air-management plan relates to the installed emitter design and drain routes. Do not assume an emitter feature removes the need to review the network. The broader operating and maintenance context is covered in our subsurface drip irrigation guide.
A connection diameter does not describe how much air an assembly will pass under the relevant conditions. Ask for the applicable air-intake and air-discharge performance data, the pressure basis, and the selected operating case. Keep the units exactly as defined by the manufacturer; do not silently mix air volumes stated at different reference conditions.
The BERMAD C10 technical sheet, July 2016, illustrates separate performance information and optional anti-slam and inflow-prevention arrangements. Those options show why accessories must be identified. An arrangement deliberately restricting air entry cannot automatically be substituted for one intended to admit it.
Ask the designer to document filling, normal operation, planned draining, and relevant pump-stop cases. Air-valve selection is part of that review, not a promise to eliminate every pressure transient. Do not create an uncontrolled shutdown to demonstrate protection. Use the approved operating and commissioning procedure for the actual pipeline.
Inspect the entire connection between the pipe and atmosphere. Record the riser, service isolation, outlet arrangement, and access for the selected valve. An appropriate device on the drawing is of little use if its connection is blocked, its service valve is left closed, or nobody can safely reach it for inspection.
| Detail | Field check |
|---|---|
| Mounting and support | Confirm the required orientation and support of the complete assembly |
| Connection path | Identify restrictions, closed isolations, and departures from the approved drawing |
| Air outlet or inlet environment | Check for soil, vegetation, flooding, or an added fitting that could obstruct the intended function |
| Service access | Provide a way to identify, isolate, depressurize, inspect, and reassemble the device |
| Documentation | Match the installed model and accessories to the schedule and manual |
Do not attach a convenient hose or cap without checking its effect with the supplier. Before opening any pressure-containing component, isolate its water supply and release trapped pressure using the approved procedure. Keep the person servicing it clear of possible discharge paths, and restore the documented operating state afterward.
Commissioning should establish what happens at the protected pipe section, not merely whether the air valve is visible. Agree beforehand on observation points, permitted operating changes, and acceptance criteria. The installer should be able to explain which evidence supports each intended function.
| Stage | Record |
|---|---|
| Before filling | Installed identity, connection state, approved start sequence and observation locations |
| Controlled filling | Observed discharge behavior and the pipe conditions during the approved filling sequence |
| Stable irrigation | Active sectors, local pressure and flow observations, persistent leakage or abnormal behavior |
| Approved shutdown | Valve states, drain routes, relevant pressure observations and any unresolved condition |
A brief release sound alone does not establish adequate intake capacity, and the absence of a sound is not a complete fault diagnosis. Where the design requires evidence about a pressure transient or sub-atmospheric condition, specify suitable instrumentation and competent interpretation. Do not infer the full pressure history from one ordinary gauge reading.
Record when a problem occurs: initial filling, normal irrigation, a neighboring block transition, or shutdown. Preserve the operating combination. Several causes can produce similar symptoms, so use the placement record to choose the next check.
| Observation | Next question |
|---|---|
| Recurring air-related flow disturbance | Is there an unreviewed crest or a release path disconnected by an isolation? |
| Concern about soil entry after shutdown | Can the affected higher lateral section reach the intended air-admission device? |
| Persistent water leakage from a vent | Do condition, contamination, pressure, or assembly details require the model’s service procedure? |
| Air valve sits in a flooded or obstructed pit | Does the environment allow the intended air path, and what corrective arrangement is approved? |
| Behavior changes after maintenance | Were the service isolation, accessories and connection restored as documented? |
Use the irrigation valve maintenance checklist for routine inspection planning. For a placement problem, retain the symptom, location, operating state, and corrective decision together. This makes the next visit a comparison against evidence rather than a repetition of guesses.
1. High points along the pipeline elevation profile; 2. Downstream of pump discharge check valves; 3. Long flat horizontal runs (every 500–800 meters); 4. Slope decrease points where steep runs flatten; 5. Dead-end terminal manifolds.
Trapped air rises to high points, constricting the cross-sectional water flow area. This creates an artificial throat (vena contracta), dramatically increasing flow velocity, inducing severe friction head loss, and causing pump dead-heading.
Combination valves feature dual orifices: a large orifice to exhaust hundreds of cubic meters of air during initial startup, and a microscopic automatic orifice to continuously vent dissolved air bubbles that escape solution under operating line pressure.
The branch riser pipe must be at least 1/3 to 1/2 of the mainline pipe diameter (e.g. at least 2" riser on a 6" mainline) to reduce water velocity in the riser neck and let rising bubbles decouple from the horizontal flow stream.
Products relevant to this irrigation guide.
Blank PE lateral pipe for drip irrigation lateral lines and micro irrigation distribution.
Thick-wall round drip pipe with inline emitters for permanent installations in orchards and vineyards.
Thin-wall flat drip tape for cost-effective row crop irrigation with precise emitter spacing.
Cylindrical inline drip tape with turbulent flow emitters for uniform water distribution in row crops.
