What purchasing parameters does Venturi Valve need to provide?

1. First, Specify the Valve Application Location

The control logic of the same Venturi Valve varies depending on where it is installed. The purchaser should specify whether the valve is used for:

• Laboratory supply air;

• General room exhaust;

• Fume hood exhaust;

• Biosafety cabinet or equipment exhaust;

• Constant-air-volume systems;

• Variable-air-volume systems;

• Room pressure control systems.

For example, a fume hood exhaust valve needs to adjust the exhaust airflow rapidly according to the sash height. A room supply-air valve must follow the total exhaust airflow while maintaining the specified offset between supply and exhaust air.

Therefore, the application location directly affects the selection of the actuator, response speed, and control program.

2. Provide the Minimum, Normal, and Maximum Airflow

Airflow is a core parameter in Venturi Valve selection. Providing only one design airflow value is insufficient. The following values should be specified separately:

The supplier uses the minimum-to-maximum airflow range to determine the valve diameter, valve core calibration range, and turndown ratio.

If the valve is oversized, the normal airflow may remain in the lower end of the control range for long periods. If the valve is undersized, resistance and noise will increase, and the valve may be unable to achieve the maximum design airflow.

When one valve cannot cover the project airflow range, two or more valves may be installed in parallel according to the control strategy. Control signals and airflow distribution must also be considered.

3. Confirm the Available Operating Differential Pressure

The term “pressure-independent” means that a Venturi Valve maintains the set airflow through valve core compensation or actuator adjustment within the operating differential pressure range specified by the manufacturer. It does not mean that the valve can operate normally at any pressure.

The following information should be provided during procurement:

• Minimum available differential pressure across the valve;

• Normal operating differential pressure;

• Maximum possible differential pressure;

• Fan design static pressure;

• Pressure loss in the most unfavorable duct run.

If the minimum differential pressure is insufficient, the valve may not achieve the target airflow even when fully open. If the differential pressure is too high, system noise and fan energy consumption may increase.

Therefore, the operating pressure should be verified during the design stage using duct resistance calculations and fan-selection data.

4. Provide Duct Dimensions and Installation Conditions

The purchaser should specify the circular or rectangular duct dimensions, connection type, installation direction, and available site space. It is also necessary to indicate whether elbows, transitions, tees, silencers, or other equipment are installed upstream or downstream of the valve.

The following information should also be confirmed:

• Nominal valve size and connection dimensions;

• Flange, socket, or other connection type;

• Horizontal or vertical installation requirements;

• Distance between the valve and elbows or duct transitions;

• Maintenance space for the actuator and controller;

• Lifting method and allowable weight.

When installation space is limited, a duct layout drawing should be provided before ordering to avoid conflicts between the valve, actuator, maintenance access, and building structure.

5. Specify the Control Method and Signal Interface

Venturi Valves can be divided into mechanical constant-air-volume models and motorized variable-air-volume models. For variable-air-volume applications, the control and feedback requirements should be provided, including:

• 0–10V or 2–10V analog signals;

• On/off or other control methods;

• Airflow setpoint and actual airflow feedback;

• Modbus, BACnet, or other communication requirements;

• Interface with the BMS or laboratory control system;

• Fail-safe position after power failure;

• Actuator supply voltage;

• Required response time.

For fume hood control, specify whether the valve must be linked with a sash-position sensor or face-velocity controller.

For room differential-pressure control, the control logic between the supply valve, exhaust valve, and differential-pressure sensor should be clearly defined.

6. Specify the Air Medium and Corrosion-Resistance Requirements

The operating conditions of normal supply air and laboratory exhaust air differ significantly. The purchaser should provide the air temperature and humidity and specify whether the air contains acidic or alkaline gases, organic solvents, particles, or other corrosive substances.

The following configurations can then be evaluated:

• Aluminum alloy, stainless steel, or other valve body materials;

• Corrosion-resistant surface coatings;

• Corrosion resistance of sealing materials;

• Actuator protection rating;

• Requirements for insulation, noise reduction, or special cleaning.

For corrosive laboratory exhaust, attention should not be limited to the external surface of the valve body. The compatibility of the valve core, springs, fasteners, and sealing materials with the relevant medium must also be confirmed.

7. What Additional Requirements Should Be Provided for Engineering Projects?

Hospital, laboratory, and biosafety projects usually need to specify:

• Airflow control accuracy;

• Target room pressure differential;

• Allowable noise level;

• Leakage class;

• Factory testing requirements.

If the project requires third-party testing, airflow calibration data, material certificates, control wiring diagrams, equipment labels, or commissioning reports, these requirements should be included in the technical specification during the quotation stage to avoid additional requirements after delivery.

8. Frequently Asked Procurement Questions

Can a Quotation Be Provided Using Only the Duct Diameter?

A preliminary quotation can be provided, but accurate selection cannot be completed. The same diameter may correspond to different airflow and valve core calibration ranges. The operating differential pressure and control method must also be confirmed.

Is a Larger Venturi Valve Always Better?

No. An oversized valve increases costs and may cause the normal airflow to remain in the lower end of the control range. The valve should be selected according to the minimum, normal, and maximum airflow.

Can a Constant-Air-Volume Model Be Converted to a Variable-Air-Volume Model Later?

Some products can be equipped with additional actuators or control components, but not all structures support this modification. Future connection to a room control or BMS system should be specified before procurement.

9. Yueboyang Venturi Valve Selection Solutions

Jiangsu Yueboyang Purification Equipment can assist with checking the airflow range, operating differential pressure, valve dimensions, control signals, corrosion-resistant configuration, and installation conditions according to the supply and exhaust requirements of laboratory, hospital, and cleanroom projects.

Purchasers are advised to submit the airflow schedule, duct layout, control schematic, and medium description. Based on this information, Yueboyang can complete valve configuration and interface confirmation, helping reduce the risks of incorrect valve sizing, insufficient airflow, control-system incompatibility, and inadequate installation space.