The stator of a progressive cavity pump is mainly made of rubber. Because it needs to form a closed meshing cavity with the rotor, it is an interference fit with the rotor. When the rotor (main shaft) rotates and causes continuous friction, it will wear naturally.
What is a stator of a progressive cavity pump?
The stator of the progressive cavity pump is one of the essential main parts of the progressive cavity pump, also known as the progressive cavity pump bushing;
The material is usually divided into two categories:
1. Use inelastic hard materials such as metals, plastics, and ceramics;
2. Use rubber-like elastic materials (including a small amount of elastic-plastic).
At present, most stators of a progressive cavity pump are rubber-based stators;
The rotor, driven by the external power source, meshes with the stator to form a sealed cavity that separates the suction cavity and the discharge cavity so that the pump can work effectively.
Table A – Physical properties of rubber
|Performance||Natural rubber (NR)||Nitrile rubber (NBR)||Chloroprene rubber (CR)||Butyl rubber (IIR)||EPDM||Chlorinated polyethylene (CSM)||Chlorohydrin glue (CHR)||Acrylic resin glue (ACM)||Chlorinated rubber (EPM)||Polyurethane rubber (Pu)|
|Vulcanized rubber hardness [Shore (A)]||30 ~ 95||30 ~ 100||40 ~ 90||40 ~ 85||30 ~ 85||50 ~ 95||40 ~ 90||60 ~ 80||60 ~ 80||> 30|
|Tensile strength /Mpa||< 18||< 20||< 20||< 16||< 20||< 16||< 18||< 13||< 12||< 40|
|Operating temperature range /℃||-55 ~ 100||-30 ~ 120||-20 ~ 120||-40 ~ 150||-50 ~ 150||-30 ~ 125||-40 ~ 150||-20 ~ 200||-20 ~ 250||-20 ~ 80|
|Compression set resistance||●||●||○||△||○||○||△||●||●||●|
|Best performance||Good elasticity, high strength, good low temperature performance and optimal dynamic performance||Turbidity and heat resistance||Acid and alkali resistance, water resistance, ozone resistance, self extinguishing||Water resistance, steam resistance, good air tightness||Aging resistance, chemical resistance, insulation, temperature resistance||Aging resistance, ozone resistance, chemical resistance||Heat resistance, cold resistance, good solvent resistance||High temperature resistant oil, halogen resistant, heat resistant||High temperature resistance, excellent media resistance||Optimal wear resistance, high lightness, high elasticity|
Note: ●: Excellent performance ○: Good performance △: Poor performance ×: Very poor performance
Table B – Rubber’s media resistance table
|Material||Maximum temperature||Suitable media||Unsuitable media|
|Natural rubber (NR)||70 ℃||The mixture of abrasive substances, a mixed liquid of organic matter, acid, alcohol, acetaldehyde, mud, cement slurry, cement||Ozone, concentrated acids, fats, oils, hydrocarbons (methane, ethylene, benzene)|
|Nitrile rubber (NBR)||90 ℃||Hydrocarbons, weak acids, weak bases, light gasoline, mineral oils, animal and vegetable oils, fats, lubricants||Aromatic hydrocarbons (substances with benzene), chlorohydrocarbons, esters, acetaldehydes, ketones, ozone, strong acids|
|Chloroprene rubber (CR)||90 ℃||Ozone, fat, paraffin-based lubricating oil, volatile lubricating oil, fatty hydrocarbon, reducing agent, salt solution||Strong acids, ketones, esters, aromatic hydrocarbons, chlorohydrocarbons, aromatic lubricants, acetic acid|
|Fluorosulfonylated polyethylene glue||110 ℃||Alcohol, salt solution, ammonia, acid chemicals, oil, bleach, disinfectant, paper, mud, chromic acid||Strong acid, crude oil, tar, aromatic carbon compound, chlorohydrocarbon|
|Fluororubber (EPM)||180 ℃||Aliphatic hydrocarbons, aromatic hydrocarbons, halogen hydrocarbons, oils, fats, acids||Ketones, esters|
|Ethylene||110 ℃||Ozone, hot water, strong sulfuric acid, nitric acid, animal and vegetable oils, fats||Petroleum, solvent, benzene, aromatic hydrocarbon, light oil, tar|
|Chloroprene rubber (VE)||120 ℃||Mineral oil (high temperature), animal and vegetable food oil, latex, rubber, paste-like solvent||Water, aromatic hydrocarbons, alcohol, ketones, alkalis, acids|
|Sodium rubber||80 ℃||Sewage, abrasive material mixed liquid, acid sludge, ammonia, inorganic sewage mixed liquid||Same as natural rubber, other ketones and fats|
|Butyl rubber (IIR)||110 ℃||Animal and vegetable oils, oils, fats, ozone, strong acidification drugs, acids, alkalis||Petroleum, solvents, benzene, aromatic hydrocarbons, light gasoline, lubricating oil|