When the Wilkins 975 XL fails, sometimes it is because the diaphragm becomes brittle over time or gets a tare. The 974-43 is the diaphragm that creates a seal in the relief valve which gives way if there is a failure in one of the checks on the back flow preventer. The relief valve is crucial to the proper function of the 975XL backflow preventer and should always be in excellent condition.
- Zorn delivers total building solutions for new construction and retrofit applications that enhance any building's environment
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- Works with either the 3/4" or 1" Wilkins 975XL double check back flow preventer