Nuclear Engineering; Off-Shore Technology; Fungus-Resistant Compounds; Environmentally Friendly Pressure Fluids - Parker O-Ring Handbuch

7. Applications
At request we shall be pleased to send you our catalogue of
aerospace compounds. We are at your service if you wish as-
sistance.

7.9 Nuclear Engineering

Elastomers which are produced for exposure to radiation must
satisfy quality and material tests. In addition to radiation, the
elastomer also must be compatible with the contact medium un-
der working conditions (temperature, pressure, etc).
In the majority of applications, the radiation dosage level remains
below 10 rad, a level which is attained after years of operation.
6
Practically all elastomers suffer no change of their physical prop-
erties at radiation levels up to 1 M rad ( 10
Parker has developed compounds with resistance to radiation
levels of 10 rad (see Section 6.21 Radiation). Water or steam
7
are common media in nuclear applications.
Typical general limiting conditions are:
Temperature: 10 rad
7
Compound: EPDM E 540-80
Other media can be taken from our Medium Compatibility Table,
order no. 5703 E.

7.10 Off-shore technology

Applications in the offshore industry set new problems for seal
manufacturers. Working conditions are very difficult:
 aggressive contact media
 high pressures
 wide range of temperatures.
Critical conditions occur in connection with:
 oil additives causing chemical attack
 explosive decompression
 clearance gap extrusion at high pressure
 high and low temperatures.
Contact media are gas, oil, water (sea water, ground water), sour
gas, CO , steam, rinsing water, lubricants (additives in lubricants
2
such as rust inhibitors), etc.
Working conditions vary greatly to location and function.
Temperatures: up to +200 °C, plus peaks
Working pressures: 100 to 1000 bar and higher
Compounds: FKM, V 747-75, V 709-90
NBR, N 674-70, N 552-90
Specials: FKM, V 858-95
Contact our engineers regarding the above and more difficult
conditions.

7.11 Fungus-resistant compounds

With the extended use of elastomers it has become necessary to
examine a recipe for parts encouraging fungus growth.
Micro-organisms are not only found in tropical climates (e.g. in
water-hydraulic systems). Compounds are tested to MIL-STD-
810B method 508. The following table 7.6 shows compounds
which have passed the test (further compounds at request).
NBR
N 674-70
N 741-75
N 552-90
N 300-90
rad 10 J/kg).
6 4
(Parbak
compound)
Table 7.6

7.12 Environmentally friendly pressure fluids

Media can no longer be ignored by industry. Particularly in mobile
hydraulics more and more fluids are being used which, compared
to mineral oils, are marked by quicker biological degradability
and lower bio-toxicity. Biological degradability is defined as the
oxidation of pressure fluids by micro-organisms resulting in the
end products of carbon dioxide, water and bacterial matter.
Note: The additives of these media (anti-aging agents, foam in-
hibitors etc.) may not be biodegradable. Consequently, various
fluids must be disposed of as special or hazardous waste after
use – which actually does not fit the term – biologically degra-
dable.
A substance is considered quickly bio-degradable if its concen-
tration has decreased by more than 80 % after 21 days as meas-
ured by special testing methods such as the CEC-L-33-T-82 test.
According to this test mineral oils degrade merely by approxi-
mately 10 to 20 %.
The media currently in use – often referred to as bio oils as well
– have been summarised in table 7.7. In addition to typical uses
the table lists the traditional abbreviations as well as the abbrevi-
ations listed in DIN 51502 and ISO 6743/4. Sealing compounds
to be used in various fluids must be selected with great care.
Further specifications pertaining to these media are contained in
DIN ISO 15380, – Lubricants, Industrial Oils and Related Prod-
ucts (Class L) – Family H (Hydraulic Systems) – Requirements
for Categories HETG; HEPG, HEES; HEPR.
143
EPDM
E 540-80
E 652-90
CR
C 557-70
Fungus resistant compounds tested according to
MIL-STD-810 B, Method 508
VMQ FKM
V 747-75
S 604-70 V 709-90
MFQ FFKM
L 677-70 V 3860-75
V 8545-75
O-Ring Handbook
Parker Hannifin GmbH
O-Ring Division Europe