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Rotary Airlock Valve : Commissioning Guide

How to commission an airlock rotary valve ?

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Section summary
1. Installation qualification
2. Operation qualification
3. Performance qualification

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The commissioning of an airlock rotary valve must follow very specific steps in order to make sure the equipment is fit for service.

This page is giving an overview of key tests to perform on the factory field to commission an airlock rotary valve through installation qualification, operation qualification and performance qualification.

1. Installation qualification

An airlock rotary valve is installed in bulk handling processes to convey and / or dose bulk materials from one area to another, typically to introduce products such as powders to a pneumatic conveying line.

The 1st step is to make sure a particular airlock rotary valve has been installed properly, even before thinking starting to rotate it for the 1st time.

The following tests are typical of a commissioning checklist of an airlock rotary valve :

• Installed valve model is as per design specification ?
• Model / brand
• Rotor Diameter
• Rotor type (number of blades...)
• Inlet and outlet flange diameter
• Material of construction
• Specific design provisions as asked during design, such as quick extraction system of the rotor
• Drive type and power
• Dust explosion safety marking (Ex...)
• Dust explosion design specificities (pressure resistance, flame proof...)
• ...
• Upstream and downstream connectors as per process design ?
• Compressed air connected to bearing seal flush (if designed to have it)
• Safety features, such as proximity switch to detect opening, are present
• Optional systems, such as detection of contact in between rotor and stator, have been installed
• No foreign body from construction work is inside the valve

2. Operation qualification

Once the Engineer is sure that the correct airlock has been installed, with the correct options and integreted properly to the process, the operation qualification can start. This time, the tests are not anymore static but the equipment will be started. It is however advised to carry out the operation qualification in 2 stages, without product then with product.

Without product :

• If possible to rotate manually the rotary valve, do so, it is to ensure that there is no contact in between the rotor and the housing, due to a damage on one of the parts or because of the presence of foreign body (safety, with the drive of the airlock rotary valve switched off and locked must be ensured)
• Start the star valve at slow speed, maybe 10 Hz on the drive, make sure the direction of rotation is correct and make sure there is no noise (scratching for instance) coming from the valve.
• If the previous test is positive, increase the speed until the target speed as per design.
• During the tests, if the valve is equipped with air pressurization of the bearing seals, make sure the air is turned on and the pressure is correct while the valve rotates (refer to the manufacturer documentation, the pressure must usually be equal to the expected pressure in the valve during operation + a certain amount).
• Stop the valve
• If it is possible to open the valve, and especially if the valve is equipped with an easy extraction system, then proceed to open the valve to make sure it is possible as designed (make sure to isolate the power before proceeding). Take the opportunity to inspect the housing as well as the rotor, blade edges, to make sure there is no damage after the initial run. Close the valve and make sure it can easily be re-assembled as per the manufacturer instructions.
• If the valve is equipped with a safety system that is detecting the opening of the valve, make sure it detected the opening and make sure the automation system interlocked the valve (and possibly other equipment around) as a consequence.
• If the valve is equipped with a system that can detect when the rotor and the stator are in contact (which can be very important for industries such as pharma or food), test it by simulating a contact.
• Perform any other tests without products required by the process in which the star valve is integrated (for example run the pneumatic conveying line fed by the valve).

With product :

• Operate the valve with product. Make sure that the valve operation is not affected by the product (no abnormal noise when the valve rotates with product). Check that there is no obvious issues with the material flow (product stuck above the valve, sticking in the vanes...).

3. Performance qualification

The performance qualification of an airlock rotary valve is highly linked to the process in which it is integrated. We assume here that the valve is used to feed a pneumatic conveying line, pressure dilute phase, which is a pretty standard function for this kind of component. The Engineer will have to customize its protocol depending on each of the applications.

• Operate the airlock rotary valve at nominal speed, make sure the capacity of the valve is sufficient vs design
• Repeat the test over longer periods of time, and for different materials to be conveyed.
• During the tests make sure :
• The temperature of the valve is not exceeding the design temperature (important as dilatation induced by temperature can seize the valve)
• There is no bridging / ratholing in the hopper above the star valve
• The venting of the airlock rotary valve is adequate
• If the valve is equipped with a rotor / stator contact detection system,
• After a series of tests, it is recommended to inspect the inside of the valve (if feasible) to make sure there is no abnormal scratch marks in the valve.