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Interlocks for butterfly valves

Butterfly valves are used where space is limited. Unlike gate valves, butterfly valves can be used for throttling or regulating flow as well as in the full open and fully closed position. The pressure loss through a butterfly valve is small in comparison with the gate valve.

In order to ensure safe operation of butterfly valves, Alcatraz Interlocks provides quarter turn interlocks, with both single and double keys in three sizes: small, medium and large.

Alcatraz integral quarter turn (DQL/SQL) valve locks fits on all type of lever operated valves/quarter turn valves such as ball valves, plug valves, 3-way ball valves, butterfly valves and even instrument valves. They are mounted on 90° rotating valves to interlock the locked open and/or locked closed position of the valve. Only if both keys are inserted in the lock portions the valve can be operated. The first key can only be released in the fully open position, the other key can only be released in the fully closed position.

Applications of butterfly valve interlocks

Alcatraz’ Interlocks for butterfly  valves can be used in multiple situations like control valve flow, ensuring safe valve operation, safe switchover of pressure safety valve systems and operation of pig trap systems. To offer the right interlock for a butterfly valve we need to understand your application and sequence of actions. To do this properly our dedicated team could assist you with measurement, commissioning and installation. Butterfly valves are common used in applications like:

Download specs for Butterfly valve Interlocks

Solutions for interlocking butterfly valves

Quarter turn interlocks: single & double key – 3 sizes: small, medium & large. Multi turn lock is also possible.

Butterfly valves utilize a lever to operate. To lock these valves we have designed different kinds of interlocks depending on your sequence (linear or nonlinear), our engineering department will design it.

Quarter turn interlocks specs: 
  • Single & double key – 3 sizes: small, medium & large
  • AISI 316
  • Material certificate 2.1 (3.1 on request)
  • Electropolishing
  • No modification to host equipment

Feature and benefits:
  • Integrated 90-degree end stops
  • Adjustable ergonomic lever
  • Mechanically programmed keys
  • Alcatraz 5 step safety integrity design

Our specialists

Meet specialist Dennis

Do you want to operate safely and prevent failures in your applications? Contact Dennis or one of our technical engineers to discuss how to do it.



Do you want to receive more information about our custom-made valve interlocks and trapped key solutions on your application? Please fill in the contact form and we will respond as soon as possible.


Electrical Key Cabinets

An Electrical Key Cabinet consists of integrated electromechanical components preventing key removal.

Spare Keys

The spare keys are intended to briefly replace a lost key until a replacement has been purchased.

Sequence control units

This is a mechanical device that is designed to fulfil client's complex non-linear Interlocking Sequence requirements.