$158.99/Each

  • Made of brass
  • Atmospheric design
  • 1/2" male connections
  • Temperature limits of 40-140 degrees Fahrenheit
  • 200 PSI maximum
  • Connections on 6" centers
UPC Code: 642889011465
Shipping: Usually Ships in 3-4 Business DaysNot eligible for expedited shipping
Fisher Backflow Prevention

Fisher Backflow Prevention

Hi, this is Jeff. Today, I'd like to talk to you about backflow prevention, but before we begin, please note that it's important for you to check with your local municipality to find out their requirements regarding backflow prevention in your area. Backflow is the unintended reversal of the normal flow of water in a plumbing system. It's caused by one of two conditions: back siphonage and back pressure. Back siphonage occurs when the normal pressure in the system turns negative, causing a reversal of the normal flow of water in the system. Back pressure, on the other hand, is when the pressure on the outlet side of the fixture is greater, causing the water to reverse itself in the water system.

Fisher offers four general types of backflow prevention. We use an air gap, we use an atmospheric vacuum breaker, a dual check valve backflow preventer, and an anti-spill pressure style vacuum breaker. Each has its own unique application. Air gap is the distance between where the water comes out of the fixture and the flood rim of the sink. You need to maintain a minimum of 2" air gap. The dual inline check valve backflow preventer is used whenever you have a flexible air gap, such as on a pre-rinse where the outlet of the device could well be below the flood rim of the sink. Atmospheric vacuum breakers commonly found on kettle fillers and service faucets are designed to prevent back siphonage. The caution is that you are not allowed to have any shut-off valves downstream of the atmospheric vacuum breaker. Anti-spill pressure style vacuum breakers are commonly found on hose reel units. They protect against back siphonage, back pressure, and it's important to note that you can have valving on the inlet side of this and the outlet side of it. And they are not to be installed above ceiling tiles in the wall, it must be accessible for inspection. Backflow prevention can be quite complex, however, in the Fisher catalog we offer many kits and components to make the process quite simple. Be sure and check your local codes. Thanks for watching.

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With four general types of backflow prevention, you're sure to find the best one to suit your needs with Fisher. Watch this video to learn all about the various fixtures you can use to help prevent backflow in your plumbing system!

Fisher 3990 Details

Prevent backflow and keep your plumbing systems up to code with this Fisher 3990 atmospheric pressure vacuum breaker assembly with 1/2" male connections. This backflow device is made of brass and features an atmospheric design which is commonly used on kettle or pot fillers and service faucets. This type of backflow preventer is made to keep water from being siphoned back into the clean water supply. It is made to operate within specific limits, including a temperature range of 40-140 degrees Fahrenheit and a maximum pressure of 200 PSI. This vacuum breaker has 1/2" male connections.

Overall Dimensions:
Connection Centers: 6"
Height: 9 5/8"

Because this item is not stocked in our warehouse, processing, transit times and stock availability will vary. If you need your items by a certain date, please contact us prior to placing your order. Expedited shipping availability may vary. We cannot guarantee that this item can be cancelled off of the order or returned once it is placed.

Attention CA Residents: Prop 65 Warning

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