Pneumatic Diaphragm Valve Air Supply Requirements: Pressure, Air Quality and Accessories

Quick Answer: The correct pneumatic diaphragm valve air supply must be matched to the actuator model, valve size, actuation mode, process differential pressure and approved manufacturer documentation; no single pressure value applies to every valve. The air must also meet the required cleanliness, dryness and filtration conditions. Start verification at the actuator inlet—or the nearest accessible downstream test point—and record both static and dynamic pressure. A normal plant-header reading can hide pressure loss across the regulator, solenoid, tubing or fittings, causing slow movement or incomplete travel even though the stationary gauge reading appears acceptable.

A pneumatic diaphragm valve needs more than a pressurized air line. The actuator must receive suitable air quality and enough pressure and flow throughout the stroke, without excessive restriction in the local pneumatic package.

This guide addresses the actuator-side pneumatic supply. Valve body process-pressure rating and complete actuator sizing are separate engineering decisions. The focus here is pressure terminology, air quality, local accessories, dynamic air delivery, commissioning and the information required for a reliable datasheet or RFQ review.

Which Air Pressure Terms Must Be Distinguished?

“Air pressure” can describe several locations and operating conditions. Using the wrong value may make a suitable plant air system appear inadequate—or conceal a valve-side restriction that prevents the actuator from operating correctly.

Plant Header Pressure, Regulated Pressure and Actuator Inlet Pressure

Plant header pressure is the pressure available in the main compressed-air distribution line. It establishes the upstream supply condition but does not show what reaches the actuator after local treatment and control components.

Between the header and the actuator, air may pass through:

• an isolation valve;
• a filter;
• a pressure regulator;
• a gauge;
• a solenoid valve;
• tubing;
• fittings;
• a speed-control device;
• an exhaust silencer.

Each item can affect pressure, flow or response time.

Regulator inlet pressure is measured upstream of the regulator. Regulated outlet pressure is measured downstream and represents the local pressure setting provided by the regulator.

Actuator inlet pressure is measured at or near the actuator air connection. It is usually the most useful value for performance verification because it reflects the condition after the local regulator, solenoid, tubing and fittings.

To see how actuator force is transferred through the stem and compressor to the sealing diaphragm, review the diaphragm valve diagram and parts guide.

Static Pressure and Dynamic Pressure

Static pressure is recorded while airflow is minimal and the actuator is stationary. It confirms that the line is pressurized but does not prove that enough air can be delivered while the actuator chamber fills.

Dynamic pressure is measured during actuator movement. When the stroke begins, airflow demand rises, and restrictions in the filter, regulator, solenoid, tubing or fittings may cause actuator inlet pressure to fall.

Adequate static pressure does not necessarily mean adequate dynamic actuation capacity.

A meaningful commissioning check therefore records pressure during a representative stroke and, where relevant, while other pneumatic equipment is operating.

Supply Pressure, Control Signal and Process Pressure

Actuator supply pressure provides the pneumatic energy used to move the actuator.

In a typical on/off package, a solenoid switches the main actuator supply and exhaust paths. A modulating package equipped with a positioner, I/P device or pneumatic controller may also have a separate command signal. In that arrangement, the supply provides the operating energy, while the signal communicates the required position or command.

The presence and form of a separate signal depend on the control package. A control signal must not be treated automatically as the actuator’s main supply pressure.

Process pressure is the pressure of the medium inside the valve body. Process differential pressure is the pressure difference acting across the valve closure. These process conditions influence the load that the actuator may need to overcome, but they are not pneumatic supply values.

Valve body pressure rating defines the allowable process-side pressure boundary. It is also separate from the actuator air-supply limit.

Pressure Terminology Matrix

For actuator review, the critical inputs include the minimum available valve-side pressure, maximum expected process differential pressure and approved actuator data. During commissioning, actuator inlet dynamic pressure and pressure recovery are the primary operating checks. For protection review, the maximum allowable supply pressure is the limit that prevents the actuator or accessories from being exposed to excessive pressure.

How Do You Determine the Required Air Pressure for a Specific Valve?

The correct pressure is established through a sequence, not selected from a universal chart:

Approved actuator documentation → valve size, actuation mode and maximum process differential pressure → site minimum, normal and maximum air conditions → actuator-side dynamic verification → manufacturer engineering review where an input remains uncertain.

Use the Actuator Model and Manufacturer Data

The actuator datasheet, product documentation or approved valve package should identify:

• actuator model and size;
• actuation type;
• permitted supply-pressure range;
• minimum pressure required for the specified load;
• air connection size and type;
• spring-return arrangement;
• applicable accessories;
• package-specific limitations.

A value published for one actuator size or one manufacturer’s package must not be transferred automatically to another design.

When the valve and actuator are supplied as an approved package, that package documentation is the starting point. When components are assembled separately, the actuator, valve, solenoid, regulator and tubing arrangement require a compatibility review.

Consider Valve Size, Actuation Mode and Process Differential Pressure

A larger valve or a higher process differential pressure may require greater actuator output. The load also changes according to whether the actuator must:

• compress a return spring;
• open against process force;
• close and seat the diaphragm;
• meet a specified stroke time;
• overcome internal friction;
• operate after an extended idle period.

Single-acting, spring-return and double-acting packages do not necessarily have the same pressure or air-volume requirements.

The RFQ should therefore state the maximum expected process differential pressure, not only the normal process condition. A valve that strokes freely during an unloaded bench test may behave differently once installed under the actual process load.

Check Minimum, Normal and Maximum Available Pressure

A useful site-air review distinguishes:

• Minimum available pressure: the lowest credible pressure at the valve location during plant operation;
• Normal available pressure: the typical regulated operating condition;
• Maximum available pressure: the highest pressure the actuator and accessories could be exposed to;
• Minimum dynamic pressure: the lowest valve-side pressure observed while the actuator moves under representative demand.

The minimum condition is used to assess whether the actuator can complete its required movement during the worst credible supply condition. The normal condition supports routine regulator setting and performance expectations. The maximum value must remain within the approved pressure limits of the actuator and accessories.

A high header pressure does not justify exposing the pneumatic package to more than its allowable pressure. Local regulation and protective arrangements must be matched to the selected actuator package.

Why Pressure Alone Does Not Confirm Actuator Sizing

Air pressure contributes to actuator output, but it is only one part of the force balance.

Available actuator force can also depend on:

• effective pressure area;
• spring force;
• stroke position;
• internal friction;
• actuator linkage or compressor geometry;
• process differential pressure;
• the force required to achieve full diaphragm seating.

Even when the supply pressure falls inside the approved range, insufficient effective area or inadequate thrust margin can still prevent full travel or the required seating force. Increasing regulator pressure is not the correct response when the package has not been shown to provide adequate actuator output.

In that situation, submit the valve size, actuator configuration, stroke and maximum process differential pressure for manufacturer actuator review. A correct air supply cannot compensate for an undersized actuator.

What Air Quality Does a Pneumatic Diaphragm Valve Need?

The valve-side air must protect the actuator and its pneumatic accessories from contamination, moisture-related problems and incompatible carryover.

The required quality is determined by the actuator construction, solenoid and positioner requirements, seal materials, ambient conditions and the project instrument-air specification.

Clean, Dry and Filtered Air

Cleanliness, dryness and filtration perform related but different functions. Filtration protects regulators, solenoid passages and other small pneumatic paths from solid contamination. Dryness reduces condensation, corrosion and freezing risk. Clean air helps prevent sticking, unstable switching and residue accumulation inside the local package.

The required filtration and dryness should be taken from the project specification and the documentation for the actuator and accessories. A requirement suitable for one component must not be assumed to cover every device in the package.

Conditions that deserve closer review include:

• large ambient-temperature changes;
• outdoor installation;
• low points in the tubing;
• retained water in filter bowls;
• cold exposed exhaust paths;
• residual moisture in the upstream air supply.

How Moisture, Particles and Oil Carryover Affect Operation

Contamination may first appear as slow response, inconsistent movement, unstable regulation or intermittent solenoid switching rather than an immediate total failure.

The CAGI Compressed Air Purity Guide explains how particles, water, hydrocarbons and downstream corrosion products can impair pneumatic equipment, while the required purity level still depends on the application.

Oil carryover is primarily a compatibility issue for seals, elastomers and internal pneumatic components. Some packages specify non-lubricated air, while other equipment may permit different conditions. The correct approach is to compare the air supply with the actuator, solenoid and accessory documentation rather than assume that every package must be oil-free or externally lubricated.

When Condensation and Freezing Become a Risk

Compressed air may release moisture as it cools. Water retained in a filter bowl, tubing low point, solenoid passage or exhaust device can restrict the air path.

Cold ambient conditions increase the risk of retained water freezing in:

• small solenoid passages;
• silencers;
• speed controllers;
• tubing restrictions;
• actuator ports.

The required dryness level should be determined from the local ambient conditions, plant instrument-air specification and component documentation. Where no project-specific dew point or filtration requirement is available, commissioning should at least inspect filter bowls, drains, tubing low points, exhaust devices and cold-exposed sections.

Visible water, recurring condensation or freezing risk should trigger an air-quality review. It should not be addressed by assigning an unsupported universal dew point or filtration value.

What Components Belong in the Valve Air-supply Path?

The local pneumatic path is more than a group of connection components. It controls the pressure, air quality, filling rate and exhaust rate seen by the actuator.

Isolation, Filter Regulator, Gauge and Drain

An isolation device allows the local air supply to be shut off safely for inspection or maintenance.

A filter removes particles and may collect liquid contamination. As the element loads, it can also become a flow restriction.

A regulator establishes the downstream pressure for the actuator package. Its adjustment range and flow capability must suit the required pressure and stroke demand. A regulator may hold the selected pressure while the valve is stationary but show pressure droop as the actuator chamber fills.

A gauge shows pressure at a defined location. The reading is useful only when the measurement point and operating condition—static or dynamic—are recorded.

A drain removes collected liquid from the local air-preparation system. Drain type, accessibility and maintenance responsibility should be reviewed during package preparation and commissioning.

Solenoid Valve, Tubing and Fittings

The solenoid controls the actuator’s supply and exhaust paths. Its arrangement must match:

• actuator action;
• powered movement direction;
• actuator port function;
• required loss-of-air behavior;
• electrical voltage;
• enclosure and hazardous-area requirements;
• required airflow;
• opening and closing time.

Tubing and fittings transmit air but also create resistance. Long runs, small internal bores, repeated elbows and restrictive adapters can reduce actuator filling speed.

When the solenoid flow path, port or tubing bore is too restrictive for the actuator chamber and required stroke time, the regulator outlet may still show acceptable static pressure while dynamic filling remains inadequate. The result may be slow travel or failure to meet the specified actuation time.

For this reason, an RFQ should state the required opening and closing time together with the approximate tubing length and internal size.

Exhaust, Silencer and Speed-control Devices

An actuator must release air as reliably as it receives it. A blocked or undersized exhaust path can slow movement even when supply pressure is adequate.

A silencer reduces exhaust noise but can become restrictive when contaminated or incorrectly selected.

A speed controller intentionally restricts supply or exhaust flow to adjust stroke time. Its direction and adjustment must match the actuator arrangement.

A quick-exhaust device can support selected fast-response applications, but its use depends on actuator action, required fail behavior and environmental conditions. It is not a universal package requirement.

Pneumatic Accessory Function Matrix

Responsibility is shared. The user or EPC verifies site routing, tubing, connection, drainage, installation condition and available plant air. The valve or package manufacturer evaluates pressure limits, component flow capacity, porting compatibility and actuator-package suitability.

Physical fit alone does not establish pneumatic compatibility. During field checks, common restriction points include loaded filters, restrictive solenoid passages, long or undersized tubing and contaminated exhaust devices.

How Do Single-acting and Double-acting Actuators Change Air Requirements?

Actuator configuration changes the supply path, exhaust path and amount of compressed air used during a cycle.

For the broader utility and control decision, the manual, pneumatic and electric diaphragm valve comparison explains when a reliable compressed-air supply makes pneumatic actuation the appropriate choice.

Single-acting and Spring-return Air Paths

A single-acting actuator uses compressed air to move in one direction. A spring or another stored-energy element produces the return movement after the powered chamber is vented.

The pneumatic package must provide:

• a reliable supply path to the powered chamber;
• an unrestricted exhaust path;
• the correct switching function;
• sufficient pressure to overcome the applicable spring and process loads.

“Single acting” alone does not define the final valve position after loss of air. The result depends on the spring arrangement, actuator orientation and valve package design.

Double-acting Air Paths

A double-acting actuator uses compressed air in both directions. One chamber is pressurized while the opposing chamber is exhausted.

The package may therefore require:

• two actuator ports;
• directional switching suited to the actuator;
• sufficient flow for both movements;
• a clearly defined response to loss of electrical power or supply air.

Because both directions use compressed air, the consumption pattern and peak demand differ from a spring-return actuator.

What Must Be Reviewed Before Selecting the Air Package?

Before finalizing the solenoid and tubing arrangement, review:

• actuator action;
• actuator port function;
• required position after loss of air;
• required position after loss of electrical power;
• supply and exhaust routing;
• opening and closing time;
• accessory electrical requirements;
• the approved valve-and-actuator configuration.

Single-acting vs Double-acting Air Requirement Table

A double-acting package consumes air in both operating directions. The RFQ should therefore state the actuator action, cycle frequency and required stroke time; checking the system under a single-acting demand assumption can underestimate peak air use.

This section establishes the air path and consumption pattern for each actuator type. Whether the application requires fail-open, fail-closed or another loss-of-air response is a separate safety decision that belongs in the fail-safe review and approved manufacturer package configuration.

Use the pneumatic diaphragm valve fail-safe position guide to define the required loss-of-air position separately from the supply and consumption checks in this article.

Why Can Static Pressure Be Adequate While the Valve Still Operates Slowly?

A stationary gauge can show acceptable pressure while the valve still operates slowly. The key question is whether the air path can maintain pressure and flow as the actuator fills and exhausts.

Dynamic Pressure Drop During Actuation

When the actuator starts to move, air flows through the filter, regulator, solenoid, tubing and fittings.

Actuator inlet pressure may then decrease because of:

• regulator droop;
• limited component flow capacity;
• long tubing;
• small internal passages;
• simultaneous actuator demand;
• fast-stroke requirements.

After the stroke, pressure may recover and the gauge may again appear normal. A dynamic reading therefore provides more useful information than a stationary reading when investigating slow or incomplete movement.

The U.S. Department of Energy’s compressed-air system sourcebook notes that point-of-use restrictions in hoses, tubes, filters and regulators can reduce downstream pressure most severely when airflow is highest.

Restrictions in Filters, Solenoids, Tubing and Exhausts

Possible restrictions include:

• a loaded filter element;
• a regulator with insufficient flow capability;
• an undersized or incorrectly configured solenoid;
• long or narrow tubing;
• restrictive fittings or adapters;
• an over-restricted speed controller;
• a blocked exhaust silencer.

The restriction can occur on the supply or exhaust side. A restricted exhaust may delay movement even if the actuator receives adequate supply pressure.

Cycle Frequency, Simultaneous Demand and Actuation Time

A single valve operating occasionally may place little demand on the air system. Multiple valves moving together can create a much higher short-duration requirement.

The review should include:

• cycles per hour;
• number of valves;
• simultaneous operating sequence;
• required opening time;
• required closing time;
• actuator internal volume;
• accessory consumption;
• distance from the air source.

These inputs determine whether the short-duration peak demand may exceed the capacity of the local valve-side path. Without them, a package review may be based only on the simplified assumption of one valve operating infrequently and independently.

Air-consumption Inputs Without Performing Full System Sizing

Air-consumption inputs should be assessed together with actuator inlet dynamic-pressure readings. This helps separate a local restriction—such as a solenoid or tubing bottleneck—from insufficient upstream capacity during peak demand.

Compare these inputs with published actuator air-consumption data. Where the documentation does not provide the required value, include it as a manufacturer-confirmed RFQ item.

High cycle frequency or simultaneous movement of several valves may require a broader system-capacity review. This input list alone must not be used to size the plant compressor or receiver.

What Happens When the Air Supply Is Insufficient or Restricted?

Insufficient air delivery can cause slow, inconsistent or incomplete movement. These symptoms justify an actuator-side air-supply check, but they do not prove that the air system is the only cause.

Slow or Inconsistent Stroke

A valve may:

• open or close more slowly than required;
• show different cycle times on repeated operation;
• hesitate during movement;
• respond differently while other pneumatic equipment operates.

Possible air-side causes include dynamic pressure loss, flow restriction, unstable regulation and contamination.

Incomplete Travel or Failure to Seat

If the actuator does not develop or maintain sufficient output, the valve may not reach full travel.

Possible consequences include:

• incomplete opening;
• incomplete closing;
• insufficient seating force;
• inconsistent position indication;
• process leakage associated with incomplete seating;
• delayed response to the control command.

Process differential pressure can increase the required actuator load. A successful unloaded bench stroke does not prove that the actuator is suitable for the installed process condition.

A Controlled Air-side Verification Sequence

This sequence is limited to actuator-side air-supply verification. It does not replace mechanical diagnosis, process review or actuator sizing.

1. Record the measurement point together with static and dynamic pressure.
2. Inspect the filter, drain and regulator, including regulator behavior during movement.
3. Check solenoid switching, porting, tubing, fittings, speed controls and exhaust devices.
4. Observe full travel, cycle time, pressure recovery and representative simultaneous demand.
5. Record the actuator configuration and maximum expected process differential pressure as inputs for manufacturer review.
6. Compare the findings with the approved actuator documentation and maximum allowable supply pressure.
7. Stop increasing pressure unless the actuator and every affected accessory are approved for the higher setting; otherwise escalate the issue for manufacturer engineering review.

Limited Symptom-to-Air-side Check Table

How Should the Air Supply Be Checked During Commissioning?

Commissioning should demonstrate that the installed valve receives the pressure and flow required by the approved actuator package under representative operating conditions.

Before Applying Air

Before pressurizing the actuator:

• verify valve and actuator identification;
• identify the actuator action;
• compare the installation with the approved supply requirements;
• inspect tubing, fittings and connection types;
• check the filter, regulator, gauge and drain arrangement;
• verify solenoid function and electrical data;
• ensure the exhaust path is open;
• check the available air against the project quality requirement;
• confirm that the test can be performed safely.

Temporary plugs, shipping caps and closed isolation devices should also be checked before the first operation.

During the First Stroke Test

Apply air in a controlled manner and observe:

• direction of movement;
• complete opening and closing travel;
• solenoid switching;
• regulator behavior;
• pressure at the defined measurement point;
• exhaust behavior;
• abnormal noise or vibration;
• excessive delay;
• incomplete movement.

Where practical, begin with a controlled no-load or low-risk test before evaluating the valve under full process conditions.

During Repeated and Dynamic Operation

One successful stroke does not establish dynamic reliability.

Repeat the operation and record:

• cycle-time consistency;
• minimum dynamic pressure;
• pressure recovery;
• full travel on each cycle;
• performance during representative simultaneous demand;
• regulator stability;
• exhaust behavior;
• accessory operation.

Where an opening or closing time is specified, record the load condition, stroke direction and measurement method.

Record the Final Settings

Commissioning records should include:

• regulator setting;
• gauge and test-point location;
• static pressure;
• minimum dynamic pressure;
• pressure recovery;
• air-quality observations;
• actuator action;
• solenoid configuration;
• tubing connection;
• cycle time;
• representative load or process condition;
• final approved settings.

Commissioning Checklist

Acceptance criteria should follow the approved project documents and manufacturer instructions.

What Information Should Be Included in the Datasheet or RFQ?

Valve size alone is not enough to establish the pneumatic diaphragm valve air supply. The RFQ must combine process data, actuator requirements, control conditions and available site air.

Information the User or EPC Should Provide

Provide, where applicable:

• valve size;
• process medium;
• operating pressure;
• maximum expected process differential pressure;
• operating temperature;
• body, lining and diaphragm requirements;
• end connection;
• minimum available air pressure;
• normal available air pressure;
• maximum possible air pressure;
• air-quality information;
• tubing size and approximate length;
• required opening time;
• required closing time;
• cycle frequency;
• number of valves operating simultaneously;
• actuator action;
• required position after loss of air;
• solenoid voltage;
• electrical enclosure requirement;
• hazardous-area classification;
• feedback or limit-switch requirement.

Information the Project Specification Should Define

The project documentation may need to define:

• instrument-air quality;
• environmental conditions;
• electrical classification;
• fail-position requirement;
• maximum acceptable stroke time;
• commissioning tests;
• documentation requirements;
• applicable project standards;
• inspection and maintenance responsibility.

Missing project requirements should be resolved before the valve package is ordered.

Information the Manufacturer Must Confirm

The valve or actuator manufacturer should provide or review:

• actuator model and size;
• permitted supply-pressure range;
• minimum pressure for the specified operating load;
• maximum allowable actuator pressure;
• actuator action;
• air connection;
• required solenoid function;
• accessory compatibility;
• model-specific air consumption;
• feasibility of the required stroke time;
• restrictions associated with the selected package;
• approved installation and commissioning requirements.

When the package includes a solenoid, air filter regulator, switch box or other topwork, use the diaphragm valve drawing guide to verify that the air connection, actuator envelope and accessory scope are shown in the project drawing.

RFQ / Datasheet Checklist

A product page can show the available valve and actuator options, but it cannot replace an application-level pressure and accessory review. Ordering only by nominal valve size leaves critical information unresolved.

Where actuator-side dynamic pressure, air quality, actuator action or maximum process differential pressure is uncertain, complete the application review before procurement rather than discover the mismatch during commissioning.

After the operating inputs have been defined, review the available pneumatic diaphragm valve and actuator package options before requesting the final application review.

Frequently Asked Questions

What air pressure is required for a pneumatic diaphragm valve?

Use the approved actuator documentation to establish the required pressure, then verify it at the actuator-side supply under dynamic operating conditions. A stationary plant-header reading is not sufficient because it does not show pressure loss through the local pneumatic path.

Is there a standard air pressure for all pneumatic diaphragm valves?

No. Different actuator sizes, spring arrangements and package configurations may require different pressure conditions. A value published for one product should not be applied as a universal standard.

Where should the actuator air pressure be measured?

The preferred point is the actuator inlet or a test point immediately upstream of it. If that location is inaccessible, the regulator outlet may be used as a proxy, but it will not capture pressure loss through the downstream solenoid, tubing or fittings. Record both the measurement location and whether the reading is static or dynamic.

Does a pneumatic diaphragm valve need clean and dry air?

The actuator and accessories need air that meets the cleanliness, dryness and filtration requirements of the project and component documentation. Wet or contaminated air can restrict passages, interfere with switching and increase corrosion or freezing risk.

What is the difference between actuator supply pressure and control signal pressure?

Supply pressure provides the pneumatic energy used to move the actuator. In a modulating package, a separate signal may communicate the requested position to a positioner or controller. A typical on/off solenoid package switches the main supply and exhaust without requiring a separate pneumatic positioning signal.

Can low air pressure prevent the valve from fully closing?

Yes. Insufficient actuator-side pressure or flow may contribute to incomplete movement or inadequate seating force. Actuator sizing, process differential pressure, mechanical condition and pneumatic restrictions must also be considered before the cause is assigned to the air supply.

Does every pneumatic diaphragm valve need a filter regulator?

Not necessarily as a separate local assembly. Where the upstream instrument air already meets the package’s quality and pressure-stability requirements, the local arrangement may only need the regulation, measurement and switching functions required by the design. Where upstream quality or pressure variation is uncertain, a local filter-regulator is more commonly used to protect the valve-side package.

Final Engineering Check Before Startup or RFQ Submission

A pneumatic diaphragm valve air supply cannot be approved from one plant-header pressure reading.

Before startup or procurement, verify:

• the actuator model and approved pressure limits;
• minimum, normal and maximum site-air conditions;
• the valve-side pressure measurement point;
• dynamic pressure while the actuator moves;
• air cleanliness, dryness and filtration;
• filter, regulator, solenoid, tubing and exhaust suitability;
• single-acting or double-acting configuration;
• cycle frequency and simultaneous demand;
• maximum process differential pressure;
• commissioning results;
• model-specific air consumption and package data.

The correct supply is the pressure, air quality and dynamic flow that allow the approved valve-and-actuator package to complete its required movement under the actual process and site conditions.

Where a critical input cannot be verified from site measurements, the approved datasheet or the project specification, the air supply should not be assumed adequate. Complete a manufacturer engineering review before startup or procurement.

Application / Specification Support

An air-supply assumption that has not been checked at package level may not fail until site commissioning, when slow travel, incomplete stroke or accessory rework becomes costly to correct.

For an NTGD pneumatic diaphragm valve application review, prepare the valve size, medium, process pressure, maximum differential pressure, temperature, actuator action, required fail position, available minimum and normal air pressure, cycle frequency, simultaneous-operation sequence, required stroke time, tubing arrangement and pneumatic accessory requirements.

These inputs allow the valve, actuator and air-supply package to be reviewed together before the final specification or RFQ is approved.