Natural and Synthetic Elastomers Slurry Pump Parts
Mar 16, 2021

Elastomers

The best elastomer for a specific application is the one that is the most cost effective taking into account the wear rate as well as the effect of the chemical and thermal environment.

Slurry pumps from Tobee are manufactured in a number of materials, to suit a wide range of operating conditions. Elastomeric materials, including natural rubber, synthetic rubbers and polyurethane offer unique combinations of erosion wear resistance and chemical resistance and are suitable for use in many slurry pump applications.

The proprietary natural rubber R55 is the standard elastomeric material selection for slurry pump liners, impellers and throatbushes due the exception erosion resistance of this material. However, all natural rubber compounds have a maximum operating temperature limit of 70°C and limited general chemical resistance. Synthetic rubber materials are available to overcome some of the limitations of natural rubber. 

High Performance Elastomers R55

R55 is a natural rubber compound designed for aggressive pumping applications where particles can be greater than 20mm in diameter, such as mill discharge pumping applications. Despite being optimised for larger particle applications, R55 retains the excellent resistance to fine particle wear that natural rubber is known for and is therefore widely used in all slurry pumping applications from the mill circuit through to fine tailings disposal. R55 uses the latest in rubber material technology with a combination of fillers to reinforce the rubber matrix and a cure system optimised for wear resistance to deliver the high performance R55 is known for. 

Polyurethane U38 


U38 is a polyurethane with superior wear resistance over other polyurethanes due to its chemical characteristics. Traditional polyurethanes are susceptible to hydrolysis of the polymer chain when exposed to water, acid or base for extended periods or at elevated temperatures, however U38 is specially formulated to resist hydrolysis and thus provides significantly improved operational life in wet slurry applications compared to traditional polyurethanes. It can be easily identified by its blue colour and is particularly useful in fine particle applications where “tramp” or other large foreign objects are present in the slurry. 


Synthetic Elastomers


When properly compounded, natural rubber has excellent wear resistance though the chemical resistance is not outstanding. Furthermore, the nature of the chemical structure of the polymer backbone leads to poor heat resistance above 70°C. For these chemical and high temperature applications, Tobee offers a selection of synthetic elastomers to cover a wide range of duties.


In synthetic elastomer compounds, the natural rubber polymer ingredient has been replaced with a man-made polymer engineered to resist a specific chemical environment or operating temperature. This often requires the use of new reinforcements, curatives and other ingredients specific to the chosen synthetic rubber. 

While synthetic elastomers have excellent chemical and heat resistance in comparison with natural rubber, there is a necessary trade off in that these elastomers typically show lower wear resistant in comparison to a properly formulated natural rubber. Follow table shows the results of slurry erosion wear testing performed on a range of elastomers, using an impinging jet at a 20° angle to the sample surface with entrained 750µm alumina abrasive. Clearly, synthetic rubbers are selected on the basis of their ability to survive a particular environment better than natural rubber. Although wear resistance of synthetic elastomers does not match that of natural rubbers, Tobee has devoted significant resources to ensuring that our synthetic elastomer offerings provide improved performance in comparison to other synthetic elastomer compounds.

Selection of Elastomers in Chemical and High Temperature Environments

When wear is the major factor in any elastomer selection, natural rubber is almost always the best material to choose if the slurry temperature is below 70˚C. For chemical, oil and applications with slurry temperatures above 70˚C, a range of synthetic elastomer compounds are available. The charts at the end of this bulletin can help with selection of the optimum elastomer for a specific application. 


Material Code

Material Type

Material Use

Hardness

(Shore A)


Service Temperature
Maximum (°C)



Adjacent Impeller
Tip Speed
(meters/second)


Industry

Natural Rubbers

R45

Natural Rubber

60 Shore A FGD Liner Rubber

60

70

27.5

Used in FGD

R55

Natural Rubber

Premium natural rubber for pumps

50

70

27.5

General

R71

Natural Rubber

Knife gate valve liners

65

70

-

Valve lining compound

Synthetic Rubbers

S01

EPDM


High temperature seal
material for chemicals


60

150

-

Alumina, chemical, fertiliser

S02

EPDM

High temperature wet ends

50

120

25

Alumina, chemical, fertiliser

S03

EPDM


High temperature low creep
seals


50

150

-

Alumina, chemical, fertiliser

S12

Nitrile


Oil resistant rubber for
impeller, liners & seals


52

95

27

Petrochemical, fertiliser

S16

HNBR

Oil & heat resistant rubber

72

170

27

Petrochemical

S18

Nitrile

Oil resistant rubber for seals

55

95

-

Petrochemical, fertiliser

S31

Hypalon


Good chemical resistance for
pumping


65

110

30

Chemical, flotation

S42

Neoprene


Good wear & Hydrocarbon
resistant rubber


49

100

27.5

Chemical, gold, copper, nickel, tar

S44

Neoprene


Hydrocarbon resistant rubber
for seals


75

100

-

Chemical, gold, copper, nickel, tar

S52

Fluoroelastomer


Chemical and temperature
resistant rubber


74

180

27

Chemical, high temperature

S90

Neoprene


Hydrocarbon & hot water
resistant


60

100

27.5

Oil sands, petrochemical

Polyurethanes

U03

Polyurethane


High Hardness wear resistant polyurethane


95

70

30

General, gold, copper, lead, zinc

U38

Polyurethane


Standard wear resistance polyurethane


82

70

30

General, gold, copper, lead, zinc 


Warman Rubber Parts