How to Connect a Back Flow Prevention Valve

Back flow valves know as "one way check valves," are used in many vehicle hydraulic applications. One way check valves come in two predominant types--ball checks and flapper valves. Ball check valves have a ball bearing inside that plugs the orifice and prevents fluid from going back through the valve. Hydraulic pressure seats the ball and more pressure only tightens the seal. Flapper type valves use a hinged movable flap that is pushed over the orifice when pressure tries to back flow. Read on to learn how to connect a back flow prevention valve.

Difficulty: Moderately Easy

Instructions

Things You'll Need:

• Pipe wrench
• Tubing cutter
• Ferrules and hydraulic fittings
• Metal drip pan
• Line wrenches

1. Know that check valves come in a variety of sizes. In general, they are used in the vehicle braking system to prevent brake fluid from returning to the reservoir when under pressure. Either type check valves are used and installation is the same for both types. Place a drip pan under tubing and check valve to be changed.

2. Using line wrench or pipe wrench, turn the fittings counter clock wise to loosen. If any pressure remains in the line, allow it to be released while fittingd are loose. Continue turning the fittings counter-clockwise until they are completely disengaged.

3. Remove check valve from tubing and allow residual fluid to go in drip pan.

4. If fittings need replaced, now is the time to remove them by using the tubing cutter. After cutting the tubing below the fitting, remove old fitting and replace with a new ferrule and fitting. Use same procedure for the opposite fitting.

5. Place new check valve up to new fitting on one end. Use line wrench and turn clockwise until fitting is snug. Be sure the check valve is pointing in the right direction. The check valve will have an arrow embossed into the valve. Make sure arrow points in the direction of flow from the line. Use a line wrench and attach a second fitting to the opposite end of check valve. Use service manual procedures for removing air from the line and dispose of fluid in drip pan in an OSHA approved container.

Tips & Warnings

• Safety glasses should be worn during the entire procedure. Fluid under pressure can cause injury unless it is relieved per instructions.
• If hydraulic fluid gets in your eyes, flush for five minutes and seek medical help.