Bunan sesibility to chemicals

[MortenA]

We are buying a progressive cavity pump for prod. water (from an oil field). I was not involved in specifying the pump but has now discovered that it was not mentioned that the prod. water will contain various chemicals such as MeOH, TEG, emulsion breaker, scale inhibitor...

Anybody got experince that indicates that one should be carefull with regards to material selection for the stator? Currently its high desity bunan.

Best Regards

Morten

 

[CB2]

Contact the pump manufacturer with your list of chemicals, they are very good at determining compatability of the various stator elastomers. Note that the water temperature can be a critical factor.

 

[quark]

My Chemical Resistance Guide (By Wilden Pumps) says Buna-N is excellent for applications involving petroleum/oil based fluids viz., leaded gasolines, fuel oils, non synthetic hydraulic oils, kerosene, turpentines and motor oils.

It is recommended not to use for chemicals viz., Methyl ethyl ketones, methyl acetone, acetone, Formaldehyde, ethyl acetate, Isopropyl acetate, amyl and butyl acetates, Benzene, toluene, xylene, benzol, hexane, napthalene, cyclohexane, CTC, trichloroethylene, EDC, methyl and propyl chloride and chloroform.

Apart from exhaustive list of chemicals I mentioned few which are pinpointed in the guide.

Regards,

 

[MortenA]

I have send them a list - i just dont trust them blindly.

Best Regards

Morten

 

[Hush]

Buna-N is incompatible with methanol and Triethylene Glycol. Unfortunately so are the two other more popular choices HNBR (Saturated Nitrile) and Fluorocarbon (Viton). Aflas may be an option, fluorosilicone would work but has poor abrasion resistance. Recommend you consult with an elastomer supplier such as Parker or Wynn.

 

[CB2]

Progressing cavity pump manufacturers like Moyno (Springfield, Ohio) have many years experiance in the oil patch with various applications. This application should not be a problem for them as long as they are given proper application information.

Third parties have limited ability to provide really accurate information about how a particular elastimer will perform in a progressing cavity pump. In a PC pump the elastimer is constantly "wiped" and variably stressed which is quite different from say an "O" ring. The chemical compatibility of the elastimer is affected by these conditions in some applications.

 

[MortenA]

I was not going to contact any elastomer supplier since its the pump manuf. (seepex) who delivers the pump. I dont have any reason to think that they would not do their best to make a good pump. I do however feel that i should know more on the subject.


Best Regards
Morten

 

[spoolguy]

From someone who works for manufacturers of these type devices, we never say a given rubber will work in an application, especially one like this. Not because we don't have detailed knowledge of what chemicals a given rubber is compatible with but we have no way of knowing what chemical it's going to be exposed to. From your posting, there are any number of chemicals the rubber could be exposed to. Water is a very good solvent and can carry chemicals that will destroy any rubber.

All you can do is look at the chemicals that are most likely to be in this particular sample, choose the rubber compatible with these and proceed with the installation. There are no guarantees.