Developing the right material is a crucial part of the diaphragm design. From pressure requirements to chemical resistance to flexibility, the material must meet your requirements. Many cases call for a specifically developed compound for the application environment. That's another area where PIC can assist you - developing the proper compound. We work closely with our suppliers to find the proper mix for the application in mind.
The charts below offer more information on general material characteristics.
Common Rubber Compounds
NAME
ADVANTAGES
ASTM 1418 DESIGNATION
ASTM D2000 DESIGNATION
Butyl
Low permeation to many gases. OK in vegetable oil and oxidating chemicals
IR
BA
Ethylene-propylene
Very good in hot water, low pressure steam and heat resistant.
EP or EPDM
CA
Neoprene
Good oil, ozone and weather resistance. Good general purpose materials.
CR
BC or EB
Nitrile
Good general purpose oil and fuel resistant material.
NBR
BF, BG, BK, or CH
Epichlorohydrin
Similar to NBR with good aging and wider temperature range. Ozone resistant.
ECO
CH or DH
Polyacrylate
Oil and heat resistant to 350°F. Good in transmission fluids.
ACM
DH, DF
Ethylene-acrylic
Oil and heat resistant to 350°F. Good in transmission fluids. Better low temperature than ACM.
EA or EAM
CH
Silicone
Good dry heat resistance and low temperature. Good ozone and weather resistance.
VMQ
GE
Fluorosilicone
Oil and fuel resistant. Wide temperature range.
FVMQ
FK
Fluorocarbon
Oil and fuel resistant. High temperature resistance.
FKM
HK
Key Properties of Common Compounds
NAME
TYPICAL TEMPERATURE SERVICE RANGE
OIL (1) RESISTANCE
AIR (2) PERMEABILITY
OZONE RESISTANCE
WEATHER RESISTANCE
Butyl
-20°F to +212°F
Poor
0.37
Excellent
Excellent
Ethylene-propylene
-40°F to +350°F
Poor
9
Excellent
Very Good
Neoprene
-40°F to +250°F
Good 60% swell
14
Good
Good
Nitrile
-65°F to +250°F
Very Good 10 to 40% swell
.46 to 1.1
Fair
Very Good
Epichlorohydrin
-40°F to +300°F
Very Good 30% swell
0.7
Good
Poor (3)
Polyacrylate
0°F to +350°F
Very Good 30% swell
1.5
Excellent
Good
Ethylene-acrylic
-20°F to +350°F
Very Good 30% Swell
No Data
Very Good
Very Good
Silicone
-80°F to +425°F
Fair 80% swell
17
Good
Good
Fluorosilicone
-65°F to +375°F
Excellent 10% swell
50
Excellent
Very Good
Fluorocarbon
-10°F to +400°F
Excellent 10% swell
0.32
Excellent
Good
NOTES:
(1) Oil Test: ASTM #3 oil, 70 hours @ 70C
(2) Air Permeation X 10 8 cm 3+CM 2/CM/SEC/Atmos@ 77F
(3) This result is for straight nitrile.
