Fume Hood Venturi Air Valve | Face Velocity & Sash Control

A fume hood Venturi air valve regulates exhaust airflow as the hood demand changes while its internal cone/spring mechanism compensates for duct-pressure variation. The XICHENG family combines an ABS, aluminum or stainless Venturi body with fast actuation and either an integrated FHC10 control package or a separate FHC100 hood controller.

The page describes a complete selectable product family, not one universal package. A basic integrated arrangement can use sash position or face-velocity input to command the valve. A more extensive FHC100 arrangement can add temperature monitoring, occupancy, automatic sash motor control, anti-pinch input, lighting/fan linkage and additional I/O.

What the Product Provides

The valve assembly provides the pressure-compensating body, actuator and selected airflow-control interface. The hood-control package can add the controller, inputs, outputs, local panel connection and BMS communication required by the approved sequence. The quotation must list which items are mounted at the valve and which are supplied separately.

The valve does not independently establish a safe hood face velocity. The result depends on sash opening, hood geometry, sensor location, exhaust fan, duct pressure, room balance and field acceptance. Valve airflow performance and hood containment must both be tested.

This distinction also controls procurement responsibility. The mechanical contractor needs the valve, dimensions and duct connection; the controls contractor needs the point list, wiring and sequence; the hood supplier needs sensor and sash interface details. One coordinated submittal should show how those scopes meet at the valve package.

Choose This Product Family When

• The hood exhaust must change with sash position, face velocity or operating mode.
• A Venturi pressure-compensating mechanism is required.
• The valve must support rapid airflow changes within a 150-750 Pa working envelope.
• ABS, aluminum or stainless construction can be matched to the exhaust stream.
• The project can define minimum, normal, maximum and emergency exhaust conditions.

The product is suitable for laboratories, hospitals, pharmaceutical facilities and chemical research environments when the selected material and control package match the actual process. Automatic sash functions should be selected only when the hood, motor, safety sensors and operating rules are designed as one system.

A hood with a small routine opening and a large emergency opening may require more turndown than one body can provide. The first screening should therefore use the entire sash and airflow schedule, not only the airflow at the nominal working height.

Do Not Treat the Valve as the Complete Hood Safety System

A fast valve cannot replace the face-velocity or sash sensor, hood controller, audible/visual alarm, fan control, room pressure strategy or commissioning. The less-than-one-second configuration is a valve response reference; complete stabilization may take longer.

Where a general laboratory branch needs VAV without hood-specific I/O, use the VAV Venturi Air Valve. Where a butterfly body is preferred, compare the Fume Hood VAV Control Damper.

Key Performance, Body Sizes and Hood Airflow Selection

The values below describe available fume hood Venturi configurations. Accuracy, response and airflow range apply only when the selected body, actuator and hood-control package operate within the stated conditions. Final values belong on the valve and hood control schedule.

Family Performance References

The response value describes the high-response configuration, not every actuator or the complete room-control loop. The accuracy statement remains tied to the selected range and operating pressure. The 10,000 CMH upper value requires an applicable combined-body arrangement and must not be assigned to one valve.

Use these figures as selection boundaries, not as unconditional guarantees detached from the approved schedule. The final hood schedule should repeat the applicable pressure range, airflow modes, response configuration and controller package beside each valve tag.

ABS Body Sizes

Aluminum Alloy Body Sizes

ABS and aluminum dimensions use different conventions and cannot be mixed. Stainless steel 304/316 dimensions, coating scope and airflow range are returned on the project drawing. An aluminum value below the 80 CMH family selection statement also requires confirmation of the body, pressure and characterized setpoint range.

Check connection geometry as carefully as airflow. The external diameter, internal diameter and overall length affect transitions, supports and actuator access. A body that covers the airflow range may still be unsuitable if the installed envelope conflicts with adjacent equipment or leaves no service clearance.

Single and Multi-Valve Selection

Use one body when its published range covers every required operating mode. Dual, triple and four-body assemblies extend capacity when one body is insufficient. The combined schedule must identify individual body size and range, total minimum and maximum airflow, common connection, actuator strategy and the method used to combine feedback.

Parallel bodies can move together or operate in stages. Coordinated movement needs matched scaling; staging needs enable thresholds, overlap and a response when one body is unavailable. Verify each valve as well as total branch airflow during acceptance.

The common inlet and outlet arrangement must distribute airflow across the bodies. Poor plenum geometry can produce unequal loading even when every actuator receives the same command. The project drawing should show body spacing, structural support, actuator removal paths and how individual feedback is exposed to the controller or BMS.

Venturi Mechanism and Material Options

The shaped body accelerates airflow through the Venturi section. Differential pressure acting on the cone and spring moves the internal mechanism as duct pressure changes, helping preserve the characterized airflow relationship. The actuator changes the requested setpoint as hood demand changes.

Pressure Compensation and Fast VAV Movement

Passive compensation and active control solve different problems. The cone/spring mechanism responds to pressure variation, while the actuator responds to the controller’s airflow demand. The high-response package is designed for rapid movement, but the hood response also includes sensor, controller, duct and fan dynamics.

The 150-750 Pa range must be available at the selected valve throughout the hood’s operating modes. Insufficient pressure can prevent the required flow; excessive pressure can increase noise and energy and move operation outside the approved envelope.

Pressure independence remains conditional on correct body selection and installation. It does not compensate for a blocked cone, incorrect actuator scaling, insufficient fan capacity or a hood demand outside the characterized range. Commissioning should verify the lowest and highest required modes under representative system pressure.

ABS Fume Hood Venturi Valve

The ABS body is molded, non-metallic and identified as flame-retardant. It is published for gas below 60 C, subject to chemistry, concentration and upset-condition review. The complete material check includes the cone, rod, spring, supports, fasteners, seals and actuator-side components.

Aluminum Alloy Fume Hood Venturi Valve

The aluminum body is one-piece spun construction with epoxy coating and an optional fluorocarbon coating for selected corrosive service. The documented configuration uses corrosion-conscious internal materials. Final coating coverage and compatibility must be confirmed from the chemical list and cleaning method.

Stainless Steel Fume Hood Venturi Valve

Stainless steel 304 and 316/316L configurations are available, with an optional fluorocarbon-coated version. Stainless is relevant where cleanability, strength, temperature or corrosion requirements justify it. Exact size and flow data belong on the approved project drawing; they should not be copied from aluminum without confirmation.

For every material, include normal and upset chemistry, cleaning chemicals and condensate behavior. A surface that resists the principal vapor may still be vulnerable at fasteners, springs, seals or coating edges. Those details should appear in the returned material schedule.

FHC10, FHC100 and Fume Hood Control Integration

The control package is selected from the hood sequence, not from the valve material. FHC10 integrates a fast linear actuator with the immediate airflow-control functions. FHC100 is a separate hood controller with broader automatic-sash, sensor and output capacity.

FHC10 Integrated Control Package

The FHC10 package accepts a resistive/voltage input for sash displacement or face-velocity sensing, an occupancy dry-contact input, status and lighting outputs, and an analog airflow-feedback output. It provides an RJ12 panel port and RS485 Modbus RTU communication.

The integrated actuator is rated at 100 N with a 3.0-second, 100 mm travel reference. Power is DC 24 V +/-10%, 20 W maximum or AC 24 V +/-10%, 40 VA maximum. Final linkage, stroke use, input type and airflow scaling must be scheduled for the selected body and hood.

Integrated mounting reduces the number of separate enclosures at the valve, but it also makes mechanical fit important. Confirm the actuator envelope, linkage alignment, service access and permitted orientation before the duct is fabricated.

FHC100 Separate Controller and Automatic Sash Package

FHC100 supports sash-position or face-velocity control, temperature monitoring, occupancy input, fan/lighting linkage and external actuator control. It can also coordinate an automatic sash motor, clutch, foot switch and anti-pinch/safety inputs when those components are included in the project.

Automatic sash operation is not a universal valve feature. The quotation must list the controller, motor, drive components, position sensor, occupancy sensor, anti-pinch device, control panel and wiring. Safe movement requires functional testing at the actual hood.

Automatic lowering after an unoccupied delay can reduce exhaust demand, but it must not trap equipment, tubing or an operator’s hands. The safety sequence should define obstruction detection, manual override, alarm behavior and recovery after a failed movement.

Face Velocity, Sash Position and Airflow Feedback

Face-velocity control uses the measured velocity at the hood opening as the primary controlled variable. Sash-position control estimates demand from opening area and a characterized airflow relationship. A combined sequence may use one input for control and another for supervision or alarm.

Airflow feedback from the valve helps verify exhaust delivery but does not directly prove face velocity or containment. The point list should distinguish commanded airflow, actual airflow, sash position, face velocity, actuator position and alarms.

When sash-position control is used, the relationship between opening area and airflow must be characterized for the hood. When direct face-velocity control is used, sensor placement and filtering must avoid unstable readings. Both methods need an emergency response and a low-flow alarm independent of normal display behavior.

BMS, Alarms and Emergency Exhaust

Modbus RTU integration requires register map, address, baud rate, units and loss-of-communication behavior. Define alarm thresholds and delays for low airflow, unsafe face velocity, sensor failure, sash obstruction and controller faults. Emergency exhaust must have a clear priority over energy-saving or occupancy modes.

Applications, Package Selection and RFQ Inputs

The fume hood Venturi air valve is selected from the hood airflow schedule and control sequence. The body size must cover every required flow, while the controller package must match the sensing method, sash functions, alarms and BMS interface.

Suitable Hood Applications

The product can serve general chemistry, pharmaceutical, hospital, biological and industrial laboratory hoods when the material and control response suit the process. The same family can support a conventional manual sash or an automatic sash package. Corrosive exhaust requires review of all exposed components, not only the outer body.

Do not use the standard page to qualify radioisotope, perchloric acid, high-temperature, explosive-atmosphere or certified fire/smoke duties. These applications need their own system and material evidence.

FHC10 vs FHC100 Selection

Choose FHC10 where an integrated fast actuator/controller package can meet the sash-position or face-velocity sequence with the required local and BMS points. Choose FHC100 where the controller must remain separate, drive an external actuator, accept broader I/O or coordinate automatic sash functions.

The decision should be recorded in the control schematic. Avoid specifying both packages as interchangeable after the mechanical valve has been fabricated because mounting, wiring, stroke and supplied accessories can differ.

Use the input/output schedule to confirm the choice. A simple hood may need one demand input, airflow feedback, lighting and status. An automatic-sash hood can require several sensors, motor outputs, clutch control, safety contacts and local overrides that belong in the FHC100 architecture.

Body and Multi-Valve Selection

List minimum, normal, maximum and emergency exhaust for representative sash positions. Select one body when it covers the complete range inside the available pressure window. Use dual, triple or four-body arrangements when one body cannot cover the required maximum or turndown.

For combined bodies, define common connection geometry, control synchronization and combined feedback. The plenum must distribute airflow, and each body must remain accessible for testing and service.

Normal operation should not sit permanently at the lowest or highest characterized endpoint where avoidable. Selection margin supports balancing, sensor tolerance and future adjustment while preserving the required emergency capacity.

Project-Ready RFQ Inputs

Provide hood width, maximum opening, sash type and travel, airflow or face-velocity target, all operating modes, available duct pressure and exhaust connection. Add chemical exposure, temperature, humidity, condensate and material preference.

For controls, identify FHC10 or FHC100 intent, sash or face-velocity sensor, occupancy, temperature, automatic sash motor, anti-pinch input, fan/lighting linkage, command/feedback, BMS points, alarms and fail state. The quotation should return the valve size/material, control package, dimensional drawing, wiring diagram, point list, included accessories and commissioning boundary.

Installation, Hood Commissioning and Maintenance

The valve, hood sensors, controller and exhaust system must be commissioned together. Mechanical installation establishes the Venturi operating condition; control testing establishes the response; hood testing establishes face velocity, alarms and containment performance.

Mechanical and Control Installation

Install the valve in the approved airflow direction and orientation, support the duct independently and leave access to the actuator and internal mechanism. Preserve the connection and transition geometry shown on the project drawing. For combined bodies, support the manifold and provide access to every actuator.

Mount sash-position, face-velocity, occupancy, temperature and anti-pinch sensors where their instructions require. Route pressure tubes and signal cables so they cannot be pinched by the sash drive or contaminated by process residue.

Signal and Package Verification

Confirm 24 V power, actuator direction, full usable stroke, command and feedback scaling, RJ12 panel and Modbus settings. For FHC100 automatic sash packages, test motor direction, limits, clutch, foot switch, obstruction detection and manual recovery before automatic operation is enabled.

Document which signal controls the valve and which values are only monitored. Verify that emergency exhaust and safety alarms have priority over occupancy or energy-saving modes.

Simulate loss of each critical input. The response to a failed face-velocity sensor, disconnected sash signal, actuator fault or lost BMS communication should match the approved risk assessment and be visible to the operator.

Face-Velocity and Airflow Acceptance

Test representative sash positions and minimum, normal, maximum and emergency airflow. Compare valve feedback with an approved airflow reference, and measure face velocity across the hood opening. Observe stability, overshoot, alarm delay and recovery after rapid sash movement.

The less-than-one-second valve configuration must be evaluated separately from complete hood response. Record the actual system result rather than presenting actuator or valve movement as the containment response.

Repeat the test with representative room doors and adjacent exhaust devices operating. Room pressure changes can alter the hood result even when the valve itself follows the command correctly. Final acceptance should record both hood and room conditions.

Maintenance and Fault Isolation

Inspect the Venturi body, cone/spring mechanism, actuator linkage, sensors, tubing, sash drive, wiring and alarms. Clean exposed components using a material-compatible procedure. Recheck airflow and face velocity after work that affects the valve, sensor, fan or hood opening.

For a fault, compare sash position, face velocity, airflow setpoint, valve feedback, actuator position, differential pressure and fan status. This separates a valve issue from sensor drift, controller logic, duct pressure, sash obstruction or room-balance changes.

Related Fume Hood and Venturi Products

Use the VAV Venturi Air Valve for general laboratory supply or exhaust, or the Fume Hood VAV Control Damper when a butterfly body is preferred. Browse all Venturi Air Valves and Laboratory Air Valves & Dampers.

Frequently Asked Questions

Does the Valve Control Face Velocity Directly?

It can participate in direct face-velocity control when the selected sensor and FHC10 or FHC100 package use that value as the control input. The installed hood still requires field verification.

What Is the Difference Between FHC10 and FHC100?

FHC10 integrates fast actuation and core hood airflow control. FHC100 is a separate controller with broader I/O and automatic-sash functions when the required components are included.

Is Automatic Sash Control Included with Every Valve?

No. It is an optional FHC100 system package that requires the controller, sash motor/drive, position sensing, safety inputs and approved wiring.

Which Valve Material Is Best for Corrosive Exhaust?

Choose from ABS, coated aluminum or stainless steel after reviewing chemicals, concentrations, temperature, condensate and all exposed components. No one material is universal.

Can Several Venturi Bodies Serve One Hood?

Yes. Multi-body arrangements can cover higher airflow, but the connection, control synchronization, feedback and individual testing must be defined.

Does Fast Valve Response Guarantee Hood Containment?

No. Containment also depends on hood geometry, sash opening, sensor, controller, fan, duct system, room balance and field acceptance testing.

Contact the Xicheng Engineering Team Today

Send the hood drawing, sash dimensions, airflow or face-velocity modes, available pressure, exhaust chemistry and control requirements. XICHENG will return a valve/material selection, controller package, dimensional and wiring information, and quotation.

Manufacturing Head Office: No. 34 Zhenxing Road (Shengtaian Heavy Industrial Park B), Loucun, Guangming New Dist, Shenzhen, Guangdong, China

Direct Hotline / WhatsApp: +86 18126478161

Engineering Mailbox: fanalax@gmail.com