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Frequently Asked Questions


Can the Deringer be installed vertically?

DC and DCDA-II Deringers (20/20G and 30/30G) can be installed vertically and only vertical up, not down. RP and RPDA-II Deringers (40/40G and 50/50G) cannot be installed vertically, only horizontally. The top lid and nameplate of the device must be pointing up in a horizontal application. You cannot rotate the device on its access.

What is Deringer weight and lay length?

You can find dimensions and weight on the product page, and more detailed information on the Specification Sheet under Literature Download on each product page. Spec sheets are also on our Resources page. Deringers range from about 18 inches up to 45 inches. The smallest Deringer weighs just 38 pounds and the largest is over 400 pounds, that's an 8" with OS&Y gate valves.

Where can I find Deringer Maintenance and Repair instructions?

On each product page under Literature Download, find maintenance videos, repair instructions, Indicator Flag Adjustment Instructions, Gear Box Wiring Instructions, Tamper Switch Procedure, and more. Our Resources page also contains many helpful videos and documents.

What does the 'X' mean on Deringer models?

'X' stands for Xtreme. Deringer Xtreme models have a larger body and check valves than the connection size, this gives you a huge savings in pressure loss. For example, the 4” Deringer 20X has a 4” connection size, but it has the body and check valves of the 6” Deringer 20 backflow preventer. Learn more in this blog.

Is the Deringer USC/ASSE Approved?

All Deringer models are USC approved. Deringer 20/40s are also ASSE Approved. Find a full list of approvals on our Resources page or view the product spec sheet.

Can I remove the wires on the Deringer?

If you don't need tamper switches, then yes, you can snip off the wires. They are not needed for the functioning of the device and if you don't need them, they hang off the device, which doesn't look great.

Can I add a bypass to convert one Deringer model to another?

No, a bypass can not be added to a device in field. You cannot convert a Deringer 20 to a 30 or a 40 to a 50. You would have to return the 20 or 40 and purchase a 30 or a 50.



Other Backflow Product Lines


Why don't you carry the Magnum?

We no longer offer the Magnum product line, because we now offer the Deringer. We do carry parts for Magnum Backflow Preventers. The The Deringer product line was developed for irrigation, domestic, and fire applications, whereas the Magnum can only be used for irrigation and domestic.

Does Backflow Direct carry 10 inch backflow preventers?

No, the Deringer only goes up to 8".



Backflow Parts


How do I find the part I need?

Use the navigation bar at the top of our website to filter by the backflow model. If you need help, give us a call.



General Backflow Knowledge


What is a backflow preventer?

Backflow Prevention Devices prevent the flow of a liquid, gas, or suspended solid backwards, into the potable water supply.

What is Backflow?

Backflow refers to contaminated water that can flow backwards into a public water supply. In fire suppression systems, water can become stagnant, heavy metals and bacteria can contaminate the water. In irrigation systems, fertilizers, pesticides and other chemicals can pose a threat to the potable water supply.

Where are Backflow Preventers used?

Deringer Backflow Preventers are mainly used in fire suppression systems in commercial, industrial and residential buildings. Typically, smaller diameter backflow preventers are used in residential homes and sprinkler systems, as well as agricultural water supplies.



Other Questions


How can I track my order?

If your order has shipped, you will receive a tracking number via email. You can also find your tracking number under My Account, My Orders, then click the tab Order Shipments. If you don't see this tab and you haven't received a shipment confirmation email, then we are still processing your order.

Our standard lead time is 1-5 business days. If your product has an unusually long lead time, we will contact you.

How can I order tax-exempt?

If you or your job qualifies for tax exempt status, email your certificate to [email protected]. Once we have reviewed your certification, we will send you an email confirmation, then you can order tax free.