Kaleb Saleeby, Author at HVAC School

We all understand vacuum pump oil is the life-blood of our vacuum pumps. We know what the function of vacuum pump oil is, and how it functions. But how do we apply that knowledge when choosing the oil best suited for our pumps? Many of us simply pick up what’s in the stock room, or on the shelves at the parts house. However, there is a good possibility your stock room and suppliers don’t carry the correctly designed pump oil for our trade’s vacuum pumps. In order to understand the types of vacuum pump oil, here’s a quick review on the characteristics of pump oil:

Vapor Pressure
- The lower the vapor pressure, the deeper the vacuum the oil is rated for
Viscosity
- Medium viscosity (thickness) is used for warmer temperatures
- Lower viscosity (thickness) is used for cooler temperatures
Distillation
- The process of removing sulfur from mineral oil to refine the oil and reduce vapor pressure

It is important to understand distillation because distillation defines the application for which the pump oil is designed.

Single distilled oil is mineral oil that goes through a distillation process one time. The process reduces the sulfur content of the oil, and the resulting oil color is light brown. This oil is used for single-stage oil-sealed rotary vane pumps. The ultimate vacuum of single distilled oil is 10 microns (1 x 10-2 torr).

Double distilled oil goes through the distillation process a second time, further removing the sulfur content of the mineral oil. The resulting color is a lighter brown. This type of oil is designed for use on most two-stage vacuum pumps and has an ultimate vacuum of 1 micron (1 x 10-3 torr).

Triple distilled oil goes through yet another molecular distillation process and is devoid of sulfur or other impurities. This oil is chemically inert and is highly resistant to oxidation and reactance to other gases. Triple distilled pump oil is transparent and is designed for an ultimate vacuum of 0.6 microns (6 x 10-4 torr).

Hydrotreated oil is a high-end pump oil designed for high vacuum applications, such as industrial and science. Hydrotreated oils are inert, and achieve a higher purity than any distillation process could boast. The process by which this oil is refined involves a hydrocarbon oil being combined with hydrogen under high pressure and temperature. This removes sulfur, nitrogen, and various other impurities from the oil. This type of oil is the purest oil available (as well as the most expensive), and is clear in color. The ultimate vacuum of hydrotreated oil is not important, as this is not an oil our trade uses. However, it is important to understand some drawbacks associated with hydrotreated oils, because I have seen companies use this highly expensive oil without fully understanding the characteristics.

Distilled vacuum pump oil is mixed with specific solvents, which aid in lubrication, oxidation resistance, and foaming resistance. These characteristics are important for vacuum pump oil, as they increase the life and performance of the pump and the oil itself. Hydrotreated pump oil, however, does not share the same solubility as distilled pump oil. This means hydrotreated oils do not mix with the necessary additives our trade specific vacuum pumps require. This can lead to damage to a vacuum pump and decreased vacuum efficiency, if not used in the appropriate application.

Synthetic (Perflouropolyether) oil is the final oil we will discuss here. This particular oil is very inert, and has a molecular consistent viscosity. The non-naturally-occurring molecules of synthetic oil are uniform in composition; whereas a typical distilled mineral pump oil has a viscosity based on the average molecule size. Synthetic oil is designed specifically for highly corrosive vacuum environments that contain gases like hydrogen peroxide, chlorine, hydrogen fluoride, etc.. If a distilled mineral oil were used in these applications, it would quickly break down and end up overheating the pump due to inadequate lubrication. This type of oil is not for use in our trade.

All these different vacuum pump oils are designed for a specific application. Many of the suppliers in my area carry triple distilled pump oil, and it is on the shelves of many stock rooms. However, the ultimate vacuum triple-distilled oil is rated for is beyond the design of our trade specific pumps. Triple distilled pump oil is for use in pumps rated for continuous operation, not the intermittent operation we apply to our pumps. The typical HVAC/R technician will use either a single distilled, or double distilled pump oil. Single-stage pumps use single distilled oil, and two-stage pumps use double distilled oil. It’s fairly simple to remember. Both oils are cheaper than triple distilled oil anyway, so there is really no reason to carry triple-distilled oil on the truck or in the stock room. Next time you’re in the supply house, look at the rated viscosity and vapor pressure of the oil on the shelves.

Another vacuum pump fluid worth mentioning is flushing oil (fluid). Flushing fluid is basically a solvent oil containing high concentrations of the helpful additives already present in distilled mineral pump oil. This pump fluid can be used to clean the residual contaminants (water, oxides, etc.) from your pump leftover by the previous oil. Flushing fluid can be highly beneficial before and after use of the vacuum pump.

In summary, there are many different types of oil used in vacuum pumps, and our trade must be aware of the type of oil we use in our trade’s specifically designed vacuum pumps. In order to optimize the full performance our pumps were designed to deliver, we may sometimes need question the unspoken norms. Constructive skepticism will push our trade to the next level of professionalism and overall growth.

Know your pump, know your oil. The performance and ultimate vacuum of your pump demands you keep the correctly design pump oil in its vanes…see what I did there?

– Kaleb

References:

https://vacaero.com/information-resources/vac-aero-training/24460-vacuum-pump-oil.html

www.edwardsvacuum.com

www.vacoil.com

Tech Tips

Salamander Broiler Cleaning

January 4, 2019 By Kaleb Saleeby No Comments

This article is written by up and coming young tech and new contributor Kaleb Saleeby. Thanks Kaleb!

Recently, I came across a work order description in my dispatch that made me scratch my head.

“Clean Salamander broiler”

I had to ask the omniscient Google for answers. Turns out, it has nothing to do with vividly-colored, “fireproof” amphibious creatures! The name does, however, pay homage to 17th-century lore that salamanders could withstand the heat of a fire, and were even believed to come from fire itself.

None of this information aided me in understanding how to clean this particular type of open-air broiler, so I did more research on how the appliance was constructed, and how it operates. From my findings, the overhead broiler is a very simple design. The basic components of a gas salamander broiler are as follows:

Gas valve
Gas manifold
Fuel orifice
Distributor
Igniter
Burner
Food racks

The gas valve on the appliance I worked on was quite literally just a knob the client manually turned on or off. When open, the gas valve allows a set fuel pressure through the manifold to be fed out a single orifice, which then gets fed through the burner. The gas is spread through the burner via a distributor to feed the ceramic plates at the end of the burner. The igniter would be the next in this sequence of operations; however, the appliance I worked on did not have a functioning igniter, and the client refused replacement, resulting in manual lighting. The ceramic plates of the burner are littered with tiny holes that allow the flame to burn uniformly across the burner with little to no major fluctuation.

None of my research gave me any answers on how to clean this equipment. I reached out to Refrigeration Technologies’ Chief Executive Officer and Founder, John Pastorello for advice on what chemicals, if any, he recommended for this job. According to John, Viper HD cleaner is safe and appropriate for the cleaning of this type of broiler. Viper HD is a slightly alkaline (basically neutral on the PH scale) cleaner that will not damage the fragile ceramic burner, as long as it gets rinsed. John states,

“You will need Viper HD and a scrub brush. As long as you rinse you will not have a problem with the heating elements. On stainless [steel], you can use HD with a soft scrub. Rinse then use a stainless steel cleaner to finish. The [stainless steel cleaner] will have a mineral oil that leaves a finger proof coating and brings out the luster. This is a labor [intensive] job because of the heavily carbonaceous soil.”

The cleaning of the appliance was fairly simple, albeit frustrating. The grease and grime were the hardest part. Once everything was clean and dry, I reassembled the appliance and relit the burner. After a few minutes of allowing the flame to stabilize, the appliance was operating well and to the satisfaction of the client.

In retrospect, I probably would avoid forcing water into the burner section. The burner assembly I worked on was riveted together, and did not allow access to the inside. I have since learned that there is insulation on the inside of the burner assembly, and wetting the insulation can potentially cause issues with the equipment, even if it has been dried off. I would recommend anyone else who encounters a job like this to use a Viper HD saturated towel and wipe the ceramic burner to clean it, and then rinse with a water-damp towel. I would also recommend focusing on the distributor inside the burner, as it may be heavily caked with carbon buildup. All other steps would remain the same. I also learned that there are overhead broiler models that have a burner design that does allow you to change the ceramic plates and insulation, if necessary, to make the cleaning process easier.