How to Recharge a UMG with Red Hydraulic Fluid

Posted on Sep 08, 2017 by Kathy DeGlandon

A Crown Unitized Mud Gauge is designed to be used right out of the box and to provide years of worry-free service. With a regular, routine maintenance schedule, a Unitized mud gauge will withstand the harshest oilfield environment. If there is a loss of fluid, Crown's UMG will need to be recharged, and it is an easy matter to do so with our CKT-UMG Repair Kit. Follow these steps to recharge a UMG.


Items you will need to recharge (pump up) your UMG -- 

  • flange gauge
  • aluminum hand pump (CH103-1)
  • Red hydraulic fluid (CW-15)
  • 11/16" wrench

Recharge a UMG

  1. Fill up the aluminum hand pump with red instrument fluid.
  2. To prevent air from entering the system, pump air out of hand pump. position swivel of hand pump over fluid jug or waste bin. Pump plunger of hand pump 1 or 2 times until all air is released and fluid comes out of swivel.
  3. Connect hand pump swivel to check valve. Check valve is located on back of flange. Secure hand pump swivel to check valve. Hand tighten nut until connection is snug.
  4. Secure hand pump swivel to check valve. Hand tighten nut until connection is snug.
  5. With hand pump secured, put flange on edge of bench so that 1/2 of the flange is resting on the bench and the other is cantilevered over the side. Center hold on bottom of flange should be easily accessible. Hold hand pump by black plunger and support flange underneath.
  6. Using hand that is supporting the underside of the flange, insert finger into center hole to fell for rubber cup diaphragm.
  7. Using hand pump, pump fluid into gauge until diaphragm collapses. Diaphragm walls will collapse inward as fluid is pumped into the system. On and one-half to two pumps are all that is needed to compress sides of diaphragm. When sides of diaphragm touch, the system has been pumped up sufficiently. Caution: Over-pumping the system will cause the fluid to push the diaphragm out the flange. Do not over-fill.
  8. Once system is pumped up, remove hand pump from check valve. Replace check valve cap.


With proper service and repair, your  Crown UMG will provide years of service. Proper service and repair, such as recharging a UMG, is important to the safe and reliable operation of all Crown equipment. The service procedures recommended by Crown and described above are recommended methods of performing service operations. Some of these service operations require the use of tools specifically designed for their purposes. These special tools should be used when and as recommended. For more information or for any questions, contact our friendly, knowledgeable staff at or at 1-877-908-3790. 

Like what you're reading? Sign Up for our newsletter and be the first to read our latest blog posts.