DH Instruments MOLBLOC-S User manual

Recommendations for
molbloc-S®Installation
Instruction Sheet
The molbloc-S is a high precision metrological
instrument whose stability over time is a key component
in the performance of the molbloc/molbox™ mass flow
calibration system. molbloc-S, like any high accuracy
standard, should be handled, operated, and stored
with care. Use the following guidelines whenever
installing and using the molbloc-S.
AVOID PARTICULATE AND MOISTURE
CONTAMINATION
Particulate and moisture contamination must be
avoided. Potential sources of contamination, such as
an unclean gas supply or device to be calibrated,
should not be connected upstream of the molbloc-S
without the use of a 5 micron sintered metallic filter
upstream of the molbloc-S.
With the exception of ambient air, the molbloc-S
should only be used with dry gases. Air compressed
on-site (generally known as instrument air) should be
filtered to remove oil, moisture and particulates.
The final dew point temperature of the calibration gas
should be – 40 °C or lower.
MOLBLOC-S CONNECTIONS
The molbloc-S elements designated 5E1-S through
2E3-S have VCR face seal inlet connections and ISO-
KF Style vacuum flange outlet connections. The 5E3-
S and 1E4-S molbloc-S elements utilize ISO-KF Style
vacuum flanges for both the inlet and outlet. See the
relevant sections for further details.
CONNECTING, DISCONNECTING AND
MOUNTING MOLBLOC-S WITH VCR®FACE
SEAL FITTINGS
In making the molbloc-S flow connections, always use
soft O-rings. They allow a leak free connection to be
accomplished with minimal torque, and they provide a
source of flexibility between the molbloc-S and
elements to which it is connected, protecting the
molbloc-S from mounting stresses.
Use the following O-ring seals for making molbloc-S
VCR®connections:
MOLBLOC-S
DESIGNATOR
VCR
FACE
SEAL
SIZE
PART NO.
DHI
PART NO.
PARKER
SEAL GROUP,
O-RING DIV COMPOSITION
5E1-S
and 1E2-S 1/4 in. 102070 2-202
Fluorocarbon
rubber (FKM),
Viton®
2E2-S
thru 2E3-S 1/2 in. 102912 2-207
Fluorocarbon
rubber (FKM),
Viton®
5E3-S and
1E4-S n/a n/a n/a n/a
Making and Breaking Procedure for molbloc-S
VCR Face Seal Connection
Install the recommended soft O-ring securely against
the sealing surface in the nut of the mating fitting.
Align the mating nut with the molbloc’s male VCR
fitting and thread the nut onto the fitting. Hold the
molbloc-S with your hand, rotate the nut until
resistance is felt when the O-ring begins to compress.
Holding the molbloc-S with your hand, tighten the
nut an additional 1/2 turn. A wrench may be used
on the nut if desired, but do not tighten beyond
one half turn. If more than one half turn is needed
to make a leak free connection, the O-ring may be
damaged and should be replaced.
To break the fitting, hold the molbloc-S with your
hand and loosen the nut until it is completely
backed off.
Never use wrenches to hold the molbloc-S body.
CONNECTING, DISCONNECTING AND
MOUNTING MOLBLOC-S WITH ISO-KF
STYLE VACUUM FLANGES
The ISO-KF Style vacuum flange fitting utilizes an
internal centering ring and an external overpressure ring
clamp. The seal is affected 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, and in positive
pressures of 700 kPa (100 psig).

molbloc, molbloc-S and molbox are trademarks, registered and otherwise, of DH Instruments, Inc.
Swagelok is a registered trademark of the Swagelok Company.
Viton is a registered trademarks of DuPont deNemours Company.
Document 560050a 030502
DH Instruments, Inc.
4765 East Beautiful Lane
Phoenix AZ 85044-5318
USA
Tel [phone]
Fax [phone]
[email protected]
www.dhinstruments.com
When performing a leak test of a plumbing
system that contains the ISO-KF Style Vacuum
Flanges, do not exceed the maximum operating
pressure of the molbox: 600 kPa (87 psia) for
molbox A700k models or 250 kPa (36 psia) for
molbox A350K models!
Making and Breaking Procedure for molbloc-S
ISO-KF Vacuum Flange Connection
Place the overpressure ring past one of the
ISO-KF flanges to be mated.
Place the centering ring into the groove of the
ISO-KF flange on the outlet of the molbloc-S.
Align the mating flange against molbloc’s ISO-KF
flange, and close the gap by hand.
Hold the flanges together and move the
overpressure ring directly over the mated flanges.
Place the clamp around the mated flanges.
Swing the clamp closed. If necessary loosen the
thumbscrew 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 the molbloc-S with your
hand and loosen the wing nut until the clamp can
be separated. Remove the clamp, centering ring,
and overpressure ring.
Never use wrenches to hold the molbloc-S body,
or to tighten the clamp.
ACCESSORIES INCLUDED WITH MOLBLOC-S
SHIPMENT
One of the following accessory kits is included in the
molbloc-S shipment:
P/N 401953
molbloc-S, Sizes 1E2 and Smaller
DESCRIPTION QTY PART NO.
1/4 in. VCR Face Seal O-Ring 2 102070
16 mm ISO-KF Centering Ring 1 101544
16 mm ISO-KF Over-Pressure Ring 1 103240
16 mm ISO-KF Clamp 1 102975
16 mm ISO-KF Blanking Cap 1 103238
P/N 401954
molbloc-S, Sizes 2E2 through 2E3
DESCRIPTION QTY PART NO.
1/2 in. VCR Face Seal O-Ring 2 102912
16 mm ISO-KF Centering Ring 1 101544
16 mm ISO-KF Over-Pressure Ring 1 103240
16 mm ISO-KF Clamp 1 102975
16 mm ISO-KF Blanking Cap 1 103238
P/N 401984
molbloc-S, Sizes 5E3 and 1E4
DESCRIPTION QTY PART NO.
Adaptor, 25mm ISO-KF x 1 in NPT M 1 103307
25 mm ISO-KF Centering Ring 1 101542
25 mm ISO-KF Over-Pressure Ring 1 103241
25 mm ISO-KF Clamp 1 102121
40 mm ISO-KF Nipple, 4.8 in. long 1 103308
40 mm ISO-KF Centering Ring 2 103245
40 mm ISO-KF Over-Pressure Ring 2 103309
40 mm ISO-KF Clamp 2 103246
40 mm ISO-KF Blanking Cap 1 103310