Viscous Fluid Selection for AODD Pump Performance Testing

[c44mac]

I'm looking for suggestions of oils/viscous liquids for the performance testing of AODD pumps. Currently I only test with water, and although there are tables/formulas for calculating flow, resistance, etc. with different viscosities, I need to study pump behavior with viscous media. Looking within the range of 90-180 cSt at room temp (20°C) and I also need 150-200 gallons of this liquid, so I have been looking for industrial oils (hydraulic oils, motor oils etc.) to keep price down and availability high.
This testing will take place in a test lab so there are various safety characteristics required:
Flame/Combustion Resistance, low-to-no Odor/Fumes and Volatility.
All components in the flow path will be nitrile, stainless steel, teflon and brass so most materials should be compatible.

 

[EdStainless]

I know that you can get 100cSt White Mineral Oil.
Maybe a bit heavier also.
Odorless, clear, tasteless, and not highly volatile.
We used to buy from PetroCanada.

 

[Doug Hunter]

My first suggestion would be a motor oil. They are very available, safe, standardized, and compatible with your materials. They are available in wide ranges of viscosities and the data is very easy to obtain. I think there are lots of sources for disposal. Are you doing general research, perhaps trying to broaden the market for an existing pump product line? Is your testing occurring only at 20°C, or over a wider range of temperatures?

 

[LittleInch]

Olive oil is about 85 cP at 20C and very cheap.

 

[c44mac]

I know that you can get 100cSt White Mineral Oil.
Maybe a bit heavier also.
Odorless, clear, tasteless, and not highly volatile.
We used to buy from PetroCanada.

Great recommendation! This appears to be a great option. I've reached out for pricing.

 

[c44mac]

My first suggestion would be a motor oil. They are very available, safe, standardized, and compatible with your materials. They are available in wide ranges of viscosities and the data is very easy to obtain. I think there are lots of sources for disposal. Are you doing general research, perhaps trying to broaden the market for an existing pump product line? Is your testing occurring only at 20°C, or over a wider range of temperatures?

Thanks Doug! I've been leaning toward motor oil but my EHS team has made it clear they would prefer something with "flame resistant" in the title, ignoring the fact that most motor oils have a safe flash point above 200°C. General research, there will be many products tested. I have suggested that we buy a chiller and give ourselves the ability to change the viscosity without changing fluids but the interest in the idea wasn't mutual, so testing will occur at 20°C or whatever the temp rises to with friction during testing.

 

[georgeverghese]

At these high viscosities, there is a high probability that any liquid you find suitable may be a non Newtonian liquid, ie. viscosity is also a function of shear rate, and this property may not be acceptable for these tests.

 

[LittleInch]

How about a water glycerol mixture? There are many websites which give you the mixture to get to your required viscosity which looks like 40% glycerol

 

[btrueblood]

Olive oil can/has acidic compounds in it that will react with the brass components over time.

Motor oils have a pretty high flash point at room temperature, so flammability ought not be a problem. But, whatever - Skydrol hydraulic fluid is fire-safe (ish), though has its own toxicity problems. DOT3 brake fluid and DOT5 silicone brake fluids are similarly fire resistant fluids.

Molasses and sugar syrups have high-ish viscosities. Molasses can have a high sulfur content, and would also react with brass and form a dark patina over time.

You can mix water and corn starch to create ooblek, a non-Newtonian (shear rate dependent) viscous fluid, but it would likely not pump in a diaphragm pump.

 

[Doug Hunter]

Thanks Doug! I've been leaning toward motor oil but my EHS team has made it clear they would prefer something with "flame resistant" in the title, ignoring the fact that most motor oils have a safe flash point above 200°C. General research, there will be many products tested. I have suggested that we buy a chiller and give ourselves the ability to change the viscosity without changing fluids but the interest in the idea wasn't mutual, so testing will occur at 20°C or whatever the temp rises to with friction during testing.

Hi C44mac,

Good luck with your EHS folks. Regarding the test temperature, your reply suggested that it would be left uncontrolled. I recommend against that, unless you plan to test with an extremely large oil reservoir. I think you'd be best served to control the oil temperature (even at 20°C) in order to keep a constant viscosity throughout your test, otherwise you won't be able to properly interpret your performance test results. Are you doing performance testing (measuring flow rate, analyzing efficiency, etc.), or only durability testing?