
The use of a vacuum pump, connected downstream of
the molbloc-S, increases the usable flow range of
each element. The installation and operation of the
vacuum should be in accordance with all applicable
local electrical, plumbing, building, and safety codes.
This instruction sheet is a guide to the application of
the vacuum system and use with the molbloc-S and
molbox Mass Flow Calibration System. Please follow
the recommendations and installation information
provided in the Pump’s Operation manual published
by its manufacturer and provided with the pump.
Installation and Use of Medium-Flow
Vacuum Pump Kit for molbloc-S
P/N 401940 & 401883
Installation Instructions
• In order to minimize the back-pressure applied to
the exhaust of the pump, plumbing should be as
short and as large in diameter as is practical, but
no smaller than the pump’s exhaust fitting size.
Inlet plumbing length and diameter should follow
the same guidelines in order to maximize the
efficiency of the vacuum pump. Restrictions in the
inlet plumbing will reduce the pumping speed of
the pump.
• In cyclic operations, such as flow meter calibrations
with molbloc-S, the pump should not be switched
off during cycles. Continue to run the pump with
the gas ballast valve open and the inlet port closed.
Power consumption is minimal when the pump is
operating at its ultimate pressure. Limit starting
the pump to no more than a few times per day.
®
VACUUM PUMP INSTALLATION,
GENERAL CONSIDERATIONS
• The vacuum pump should be located in a place
where there is adequate ventilation for cooling.
Consideration of the noise and heat generated by
the pump should be made. It might be desirable
to install the pump in a location outside of the
laboratory in which the molbloc/molbox system is
operating.
• Caution should be exercised when calibrating in
gases other than air. Asphyxiation of personnel
within a confined space into which the pump
exhausts is a real threat when calibrating at high
flow rates. Venting of the exhaust gas stream
outdoors or into a large ventilated space is
recommended.
TECHNICAL DATA
Pumping Speed
Average Noise Level
Main Voltage
Motor Power
Nominal Speed
Weight w/oil
Oil Capacity
Inlet/Outlet Connection
64 cu m/hr. (37.7 cfm)
69 dB(A)
(free field measurement at 1 m)
50/60 Hz Volts
230/460 (± 10 %), 3-Phase Supply
1.8 kW (2.5 hp)
1 750 RPM
47 kg (103.4 lb)
2.0 l (2.11 qt)
1 1/4 in. Female NPT

DIMENSIONAL DATA, mm (in.)
Ø a
Ø b
A
H h1 h2 h3 X Y Z
in.
max
695
(27.4
)
260
(10.2
)
237
(9.3)
216
(8.5)
270
(10.6
)
NPT
1 1/4
in.
NPT
1 1/4
350
(13.8
)
100
3.9
150
(5.9)
VARIATIONS, mm (in.)
This pump kit is available in two versions.
STANDARD PUMP KIT
P/N 401940
LUBRICATION
TYPE
SERVICE
DETAILS
Paraffin-base
Mineral Oil
General Purpose
– pumping air and
chemically inert
permanent gases
Please read and understand the enclosed Installation
and Operation Manual, Material Safety Data Sheet,
and all other enclosed data. Personal injury and/or
property damage could result if this equipment is not
installed and operated properly. This system should
be assembled and operated only by personnel who
have been instructed in proper safety practices.
PFPE PUMP KIT
P/N 401883
Perfluorinated
Polyether (PFPE)
Special Purpose
– pumping strong
oxidants such as
oxygen, ozone,
nitrogen oxides
Ø a
Ø b
A
a0 a1 a2 a3 a4
NPT
NPT
1 1/4
1 1/4
in.
in.
B b1 b2 b3 Ø D/P
100
3.9
max
695
(27.4)
150
(5.9)
260
(10.2)
1 1/4
in.
237
(9.3)
(8.5)
216
1 1/4
in.
270
(10.6)
350
(13.8)
695
(27.4)
molbloc-S is a trademark, registered and otherwise, of DH Instruments, Inc.
Document 560053-01 030502
DH Instruments, Inc.
4765 East Beautiful Lane
Phoenix AZ 85044-5318
USA
Tel 602.431.9100
Fax 602.431.9559
dhi@dhinstruments.com
www.dhinstruments.com