molbloc-S and molbox are trademarks, registered and otherwise, of
DH Instruments, Inc.
Viton is a registered trademarks of DuPont deNemours Company.
Document 560052
021119
DH Instruments, Inc.
4765 East Beautiful Lane
Phoenix AZ 85044-5318
USA
Tel 602.431.9100
Fax 602.431.9559
www.dhinstruments.com
INSTALLATION OF MEDIUM VACUUM
PUMP DOWNSTREAM INTERCONNECT KIT
The above figure shows the basic interconnection
plumbing when using the Medium Flow Vacuum Pump
with the molbloc-S. This kit includes 2 conical reducers
with the ISO-KF Style Vacuum Flange ends. When
connecting a single molbloc-S to the vacuum pump,
use both the 40 mm x 25 mm, and the 25 mm x 16 mm
conical reducers. When utilizing the downstream tee
assembly (
DHI
P\N 401884) only the 40 mm x 25 mm
conical reducer is required.
For the sake of flexibility this interconnection kit
includes a coil of 1 1/2 in. wire reinforced PVC hose.
This hose can be cut to the precise length required in
each application. Hose barb fittings slip inside the
hose and are secured by worm drive clamps.
VACUUM SHUT-OFF VALVE
The vacuum shut-off valve is provided so that the
operator can continue to run the vacuum pump while
changing the Device Under Test (DUT) or the molbloc-S
between calibration runs. It is not recommended to
start and stop the pump more than a few times per day.
Therefore continue to run the pump with the gas ballast
valve open and the vacuum shut-off valve closed.
Power consumption is minimal when the pump is
running at its ultimate pressure.
CONNECTING, DISCONNECTING AND
MOUNTING MOLBLOC-S WITH ISO-KF
STYLE VACUUM FLANGES (MOLBLOC-S
OUTLET FITTING)
ISO-KF Style Vacuum Flange Fittings
The outlet connection system on the molbloc-S body is
the ISO-KF style vacuum flange. It utilizes an internal
centering ring, overpressure ring, and an external clamp.
The seal is effected by the uniform application of
pressure by the clamp on the 15° surface of the mating
stainless steel flanges. These mating flange surfaces
compress a Viton
®
O-ring that is held in place by the
centering ring. The overpressure ring keeps the O-ring
in place, and maintains a leak free connection when
the system is subjected to internal pressures above
vacuum level. This connection is reusable, rotatable,
and can operate leak free in vacuum applications up to
10
-8
Torr. When an overpressure ring is used, KF25 or
smaller flange connections can operate leak free to
positive pressure beyond 600 kPa (87 psia)
Making and Breaking Procedure for ISO-KF
Style Vacuum Flange Connections
Place the centering ring (and overpressure ring if
applicable) into the groove of one of the ISO-KF
flanges to be mated.
Align the mating flange, and close the gap by hand.
Hold the flanges together while putting the clamp
around them.
Swing the clamp closed. If necessary loosen the
wing nut to allow the thrust washer and wing nut to
fall into position on top of the clamp. Fully tighten
the wing nut by hand.
To break the fitting, hold one of the plumbing
sections with your hand and loosen the wing nut
until the clamp can be separated. Remove the clamp,
centering ring, (and overpressure ring if applicable).
