The best oil for your hydraulic torque wrench pump
Most of the operators we work with put their hydraulic torque wrench pumps to the test on a daily basis. Meaning, they use them for long hours in the field and expose them to wide ranges of temperature. Also, if a torque pump goes down, it usually means that the rest of the operation stops as well, unless that operator has a “back up” pump on site. The good news is that there are a few steps we can take when choosing the hydraulic oil to help prevent pump down time.
One of the first things you should look for is an oil with good characteristics in providing thermal, oxidative and hydrolytic stability. First, this means that the oil will provide good power flow over wide temperature ranges. Secondly, it should have characteristics which protect metal components from scuffing, galling and other wear. Finally, the oil should withstand chemical decomposition in the presence of water.
Next, we should consider that the size of a torque wrench pump reservoir is not very large (usually <2 gallons). As such, we should ensure that the oil we choose is non-foaming and also resists oxidation. This is because oxidation leads to sludge and varnish in the oil and will promote plugged orifices and sticky valves.
An easy way to spot oxidation in oil is when the oil is darker than when it was originally added to the system. I have heard the comment that this dark color might be dirt, which is picked up in the field, during hose reconnects. However, when we open up the reservoir we have found that it is usually oxidation and foaming.