Meeting the need for a new generation of mass
flow standards
molbloc/molbox meets the growing need for a mass flow calibration
system with very high accuracy and direct traceability to national
standards that is also fast, compact and easy to use.
molbloc/molbox delivers ±0.2% of reading accuracy in the
critical range of less than 10 sccm to 60 slm .... real time,
in an easily transportable, benchtop system.
molbloc/molbox's exceptional metrology, extensive on-board features, advanced
PC software and gas handling accessories make it the ideal system for testing
or calibrating your mass flow measuring and controlling instruments. It
can also be the instrument of choice in critical flow measurement applications.
First introduced in 1993, molbloc/molbox has rapidly gained wide acceptance
in semiconductors, fibre optics, pharmaceuticals, environmental monitoring,
energy production, instrument manufacturing, research and standards laboratories
as the tool of the future in assuring the integrity of mass flow measurements.
Combining
proven theory and innovative technology to reach a new level of performance
The molbloc principle is founded on well established laminar flow theory
and the known thermodynamic properties of gases. Unprecedented levels
of
stability and accuracy are obtained by applying today's modern measuring,
mathematical modeling, data processing and manufacturing technologies
to
a new laminar flow element design so novel it has been granted US and international
patents. These allow much better definition of the flow element's geometry,
precise knowledge of gas temperature and pressure and a reduction in the
dependence on up and downstream flow conditions.
The molbox that supports molblocs uses transfer standard quality pressure
transducers and self calibrating platinum resistance thermometer circuitry.
Extensive non-volatile memory stores the complete thermodynamic properties
of all the supported gases and a powerful micro-controller executes high
speed pressure and temperature readings and mass flow calculations.
A
fundamental system backed by gravimetric primary standards for the ultimate
working calibration tool
Mass flow, mass over time, is derived from the fundamental SI units of mass
and time. Traditional volumetric and rate of rise mass flow standards are
calculable systems that determine mass flow indirectly from volume flow
and a calculation back to mass. Like molbloc, they are dependent on gas
pressure and temperature measurement and knowledge of the gas' thermodynamic
properties.
Gravimetric mass flow calibration techniques provide the only method for
deriving mass flow directly from the base units of mass and time without
the influence of secondary measurement and calculation. Until recently,
this method was not widely used as it is difficult and very time consuming
and no devices to be calibrated had the performance to justify devoting
hours or days to individual calibration points.
molbloc/molbox's unique performance characteristics change everything. The
system's excellent precision and stability justify the investment of time
needed to apply gravimetric calibration methods and make the lower uncertainties
of this truly primary technique available in every day calibrations. To
meet this potential, a unique gravimetrically based flow calibration chain
dedicated to molbloc characterization has been developed. This one of a
kind facility assures that molbloc/molbox, in addition to delivering unprecedented
precision, sets a new standard for absolute accuracy and consistency over
a wide range of flows and gases.
Configuring
a molbloc/molbox System
A molbloc/molbox system consists of a molbox, one or several molbloc elements
as needed to cover the desired flow range and additional accessories depending
on the application.
molbox 1 is the centre of the system to which molbloc mass flow elements
are connected as needed.
molbox1 Part Number:molbox1 Purpose/Description: molbox1 is the support unit for molbloc mass
flow elements. Two molbloc elements can be connected and switched or operated
simultaneously. molbox1 contains two high accuracy absolute pressure transducers
for measuring molbloc upstream and downstream pressure, valving for automated
pressure transducer switching, taring and leak checking, 4 platinum resistance
thermometer measuring circuits, a front panel display and full function
keypad. molbox1 supports RS232 and IEEE-488 host communications and extensive
mass flow controller (MFC) settings, reading and diagnostic functions.
Ordering description: molbloc terminal complete with power cord,
(4) pressure connection molbox lines, (2) molbloc connection cables, moltools
software, user's manual and calibration certificate.
options: molbox1
001: GPIB (IEEE 488) interface. Provides IEEE-488
interface for communication with a host computer.
004: Rack mount kit. Kit for rack mounting
molbox1 in standard 19" rack. molbox1 Height is 2U (8.9 cm, 3.5
in).
009: MFC control. For setting and reading mass
flow controllers and meters (MFC, MFM) in V or mA. Includes analogue
board in the molbox1 and MFC connecting kit.
012: External valve drivers. Provides 8 switchable
signals (12 V, 500 mA max per channel 1 A max total) for valve actuation
or other functions and mating rear panel connector.
MFC switchbox: Provides automated switching
between the molbox1 MFC control and up to four MFCs. Includes switchbox
connector cable to molbox1 and 3 MFC connecting kits. Requires molbox1
option 009.
molblocs Part Number:200 sccm(1) - VCR(2) - V(3)
- Q(4).
End flange fitting for flow connection (VCR,
VCO or SWG for 1/4" Swagelok)
Viton®* O-rings used to seal end flanges.
Pressure connection flange fitting (Q for quick
connect, S for Swagelok).
Purpose/Description: The molbloc is the flow
element through which the flow to be measured passes. It is connected to
the molbox by two pressure lines and a data line. One or several molblocs
should be selected based on your flow range requirements using the information
and guidelines below. Two molblocs can be connected
to the molbox simultaneously allowing easy switching between two ranges
and/or summing of two molbocs in parallel to achieve flows up 60 slm by
combining two 30 slm molblocs.
Ordering description: molbloc fundamental mass flow element in storage
case complete with installation O-rings and calibration certificate.
options: molbloc
016: Special gas calibration. Provides special
calibration of the molbloc directly with a gas other than nitrogen.
Gases other than nitrogen can be measured without this option. See below
for information on this option and gases available
molstics Part Number: molstic, XXXXX (XXXXX identifies model/application)
Purpose/Description: molstics provide a high quality, engineered
solution to the practical issues of molbloc mounting and hook up which can
have a large influence on the quality of measurements. molstics provide
everything that is needed in one compact, integrated assembly studied to
optimise performance under specific operating circumstances. Ordering description: molbloc mounting system.
CompassPDF
Data sheet download (515kB) Purpose/Description: COMPASS for molbox for Windows is IBM PC compatible
based applications software designed to optimise the use of a molbloc/molbox
system in verifying and calibrating mass flow controllers and meters. COMPASS
follows established Windows protocol for file management, menu and message
formatting, graphics and editing. COMPASS maintains test device records,
fully automates test execution and prints plots and reports. Please contact
us for more detailed information. Ordering description: Calibration assistance software complete with
3.5" installation disks and user's manual.
Note: molbox1 can support two molblocs used in parallel
to measure flow greater than 30 slm. For example, two 30 slm molblocs can
be used in parallel to measure up to 60 slm.
All values are in sccm and valid when the molbloc is operated with a downstream
absolute pressure of 200 kPa (30 psia). molbloc can be operated at other
downstream pressures to a maximum of 300 kPa (45 psia) and minimum atmospheric
pressure. When the downstream pressure is not 200 kPa, the useable range
is adjusted following:
useable range* = nominal range x (downstream pressure (kPa) +
25) / 225
*to a maximum Reynolds number of 1200 (indicated
by molbox). Ranges in bold characters are limited by Reynolds number and
cannot be adjusted upwards beyond that value.
Flow Measurement Specifications
Accuracy:
For N2 or any gas for
which the molbloc is calibrated when operated at 150 to 250 kPa downstream
pressure:
± 0.2% of reading or 0.02% full scale, whichever is greater.
For gases other than N2 supported by molbox but for which
the molbloc is not calibrated:
± 0.5% of reading or 0.05% full scale, whichever is greater.
For any molbox supported gas when operated at downstream pressure
less than 150 kPa or greater than 250 kPa:
±0.5% of reading or 0.05% full scale, whichever is greater.
Repeatability:
±0.05% of reading or 0.005% F.S. whichever
is greater.
Linearity:
Within ±0.1% of reading from
10 to 100% FS; ±0.01% FS. under 10% FS.
Reproduceability:
(one year)
±0.1% of reading, or ±0.01% FS. whichever
is greater.
Note: Systematic use of molboxl's on-board pressure transducer
taring function can improve low-end molbloc accuracy so that the full scale
uncertainty term is divided by 2.
