 Product
Overview:
A single seat diaphragm operated non return valve designed
for use in Bi-Propellant systems to prevent back flow of propellant
vapours from the propellant tanks.
The Non-Return valve is an all welded configuration employing
titanium, titanium alloy, stainless steel and PTFE for the
propellant wetted surfaces. The design is characterised by
few components, no sliding parts and a low cracking pressure,
pressure drop and internal leakage achieved by the pressure
assisted, diaphragm type of flat seal concept.
The supply pressure acting against the spring loaded diaphragm
piston lifts the sealing annulus from the mating PTFE seat
permitting the flow of gaseous helium into the system pressurant
lines. Continued flow, will at a certain time bring the system
pressure up to the level at which the pressure differential
across the diaphragm is insufficient to prevent the spring
from re-seating the seal. The valve is then closed, stopping
all flow of gas until a drop in the downstream pressure is
detected by the diaphragm and the valve starts to 'crack'
open allowing re-pressurisation.
Performance Characteristics:
| Operating Media |
GHe, NTO, MMH. |
| Operational Temperature |
-50°C to +50°C |
| Operating Pressure |
Up to 35.6 bar |
| Cracking Pressure |
< 0.20 bar |
| Re-seat Pressure |
0.085 bar max. below cracking pressure |
| Pressure Drop |
< 0.20 bar at 0.50 g/sec GHe |
| External Leakage |
< 1 x 10-6 scc/sec GHe |
| Internal Leakage (reseat) |
< 1 x 10-4 scc/sec GHe |
| Cycle Life |
5,000 operational |
| Mass |
< 85 g |
| Inlet Filtration |
10 micron absolute |
| Materials |
Titanium, Titanium alloy, Stainless steel, Teflon |
| Interfaces |
1/4” weldable Ti tubing (optional 3/8”) |
Product History:
The single element Non-Return valve was originally developed
as part of the ESA Advanced Systems Technology Programme (ASTP-4)
and qualified for the ARTEMIS Unified Propulsion System. This
unit has since been selected for use on a number of major
satellite programmes including Eurostar and Spacebus.
|
