One of the biggest problems faced by turbine operators is the threat of electrostatic discharges within oil. This is a problem that can be dangerous if left undetected, but how exactly do you uncover an electrostatic discharge problem in turbine oil?
The easiest method that enables you to determine an electrostatic discharge problem is to just listen. If you can hear a clicking noise in the area immediately around the filter or close to the oil reservoir, it is likely that you have a spark discharge issue. However, we’re sure you would agree that it is much better to take preventative measures, which will enable you to stop the problem at source, rather than wait until you already have an electrostatic problem and then try to correct it.
Preventative measures
The majority of turbine oils used at present are Group II oils, with occasional use of Group III oils being required. Since these oils require a high level of refining, they are much less conductive than many other oils on the market. As the conductivity of an oil decreases, the potential for it to be effected by electrostatic discharge issues increases. The friction between the molecules in the oil and the oil and the equipment is what develops a static discharge.
Issues that can contribute to creating a static problem include a piping system that has too narrow a diameter, which leads to an increase in flow velocity, a dearth of polar additives, a failure to adequately ground the system and low oil levels. If you can take care of these problems right from the start you will significantly cut your chances of having to deal with a spark problem at a later date.
You may also want to look in to oil analysis laboratories, which are able to perform electrical conductivity tests (ASTM D2624). Although this method was created mainly to test aviation fuels, it is known to be effective for testing electrical conductivity in industrial lubricating oils too.
If a test is conducted and oil’s conductivity is found to be over 400 piscosiemens per metre at a temperature of 20 degrees centigrade, there is almost no risk of a static discharge problem.
So, bear in mind that there are lots of things you can do to prevent an electrostatic discharge by concentrating on the conductivity of your oil. If you do all you can to keep this in control, you will never have to worry about detecting static in your oil.
