Field of the invention
The present invention relates to measurement of ultra low gauge / differential
pressure and, in particular, to a micro manometer system for the measurement of
ultra low gauge /differential pressure which would achieve an accuracy of +/-
0.1mm. wc or better. Importantly, the micro manometer system of the invention is
adapted to provide readings, which would be stable and repeatable and hence
reliable for such measurements. The system is adapted with user friendly features to
favour wide scale acceptability and use as a micro manometer system for the
measurement of ultra low gauge / differential pressure
Background art
It is well known to carry out measurement of ultra \DVJ gauge / differential pressure )
for variety of applications and, is particularly, a very common requirement in
different heating processes of steel plant.
Importantly, the measurement and control of very low value gauges/ pressures is
extremely important in various applications such as coke oven batteries and re-
heating furnaces of rolling mills. In particular, it is known that the measurement of
very low value differential pressure is very important in different re-heating furnaces
for accurate measurement and control of fuel gas flow to the furnaces. Usually, the
pressure value range between +/- 5 to +/- 25mm wc with accuracy requirement of
+/- 1 mm. wc or better.
Conventionally the pressure measurements for the above purposes are done by
electronic differential pressure transmitters and electronic indicators in conjunction.
Differential pressure transmitters usually have wide rangabihty and for calibration of
these transmitters with desired level of accuracy, pressure calibrators with accuracy
of the order of +/- 0.1mm. wc is required.
There are basically two types of calibrators with the desired accuracy, which are
available to the art. Such accuracy based calibrators include i. Electronic Calibrators
and ii) Micro Manometers.

Electronic calibrators with desired accuracy are portable, easy to operate but
required calibration at definite intervals. The cost of electronic calibrators is
moderate, however, for the calibration of such electronic calibrators, master
calibrators with accuracy better than +/- 0,03 mm, wc. is required.
Micro manometers on the other hand are much bigger in size and require stable and
larger space to operate. Advantageously, such micro manometer once calibrated,
frequent calibration is not required. However, the cost of such micro manometer is
high and for the calibration of such micro manometers, calibrator with high accuracy
such as better than +/- 0.03mm wc is required.
It is also known that to establish the calibration traceabihty of the above types of
calibrators these are required to be sent to the calibration laboratory. However,
master pressure calibrators with desired accuracy are usually still not available in
most calibration laboratories.
Objects of the invention
It is thus the basic object of the invention to provide for micro manometer system
for the measurement of ultra low gauge / differential pressure with the accuracy of
+/- 0.1mm wc. or better.
Another object of the present invention is directed to micro manometer system for
the measurement of the ultra low gauge / differential pressure with stated accuracy
wherein the reading from the system would be stable and repeatable and thus
reliable and convenient for the end user.
A further object of the present invention is directed to a micro manometer system
for the measurement of ultra low gauge / differential pressure wherein the
calibration traceabihty of the device could be easily established
Yet further object of the present invention is directed to micro manometer system
for the measurement of ultra low gauge / differential pressure involving simple U-
tube water manometer as a basic gauge thereby enabling maintaining simplicity and
ease of operation.

A further object of the present invention is directed to a micro manometer system
for measurement of ultra low gauge / differential pressure with user friendly and
ready readability features adapted to favour wide scale application and use of the
system for the measurement of ultra low gauge / differential pressure
Summary of the invention
Thus according to the basic aspect of the present invention there is provided a micro manometer system for the measurement of ultralow gauge/differential pressure comprising
a base with height adjusting means for leveling ;

a frame vertically disposed with respect to said base;
a graduated and slidable scale mounted on the said frame,
a dial-gauge mounted on the frame with a tube manometer preferably selected
form glass U-tube and single tube manometer requiring multiplication factor equal to
the ratio of cross sections of manometer tube limb and the liquid pot mounted on
the frame above said scale;
a plate means fixed to the scale adapted to pulse the plunger of the dial gauge such
that apart from the initial reading of the dial gauge for reading with fractional mm
the scale is slide to obtain the next reading.
According to a preferred aspect of the invention there is provided a micro
manometer system for the measurement of ultralow gauge/differential pressure
comprising
a base with height adjusting means for leveling ;


a graduated and slidable scale mounted on the said frame,
a dial-gauge mounted on the frame with a tube manometer preferably selected
form glass U-tube manometer and a single tube manometer requiring multiplication
factor equal to the ratio of cross sections of manometer tube limb and the liquid pot
mounted on the frame above said scale;
a plate means fixed to the scale adapted to pulse the plunger of the dial gauge such
that apart from the initial reading of the dial gauge for reading with fractional mm
the scale is slide to obtain the next reading; and
a readability improving means preferably selected from a magnifier with sliding
arrangement adapted to read the water meniscus level on the scale or eye piece
with crosswire.
Importantly, in the above disclosed micro manometer system for the measurement
of ultralow gauge/differential pressure of the invention the dial gauge for
measurement of displacement of scale favours good accuracy and repeatability! The
cooperative magnifier with longitudinal scratch provides for avoiding parallax error
and at the same time achieves desired magnification of the scale Advantageously,
the light means mounted on the magnifier provide for extra illumination.
According to another advantageous aspect in the micro manometer system for the
measurement of ultralow gauge/differential pressure the said slide means is slidable
with respect to guide means preferably step screws Importantly, for said controlled
sliding the screw arrangement is attached to the clamps with said scale and the
clamp with frame
The micro manometer system for the measurement of ultralow gauge/differential
pressure is adapted such that the displacement in the scale required to reach a next
marking is based on the difference in the two readings in the dial gauge and
preferably the scale is selected with 5 mm graduation. Preferably, the scale sliding
arrangement comprises set of gears and screws with very fine threads.

It is thus possible by way of the above discussed system for measurement of ultra
low gauge / differential pressure to avoid the limitation of the conventional devices
for gauge / differential pressure calibration and yet achieve much desired accuracy
of +/- 0.1mm. wc or better. Importantly, the system of the invention enables
reading from the device, which is stable, repeatable and thus highly reliable More
importantly, the system of measurement of the invention has been adapted such
that the calibration traceability can be easily established.
Accordingly to an aspect of the invention the system for measurement of ultra low
gauge / differential pressure while favouring measurement in the ranges of +/-
0.1mm wc. also, advantageously, makes effective combination and working relations
involving simple U-tube water manometer as a basic gadget.

While in the normal U-tube manometer the scale is graduated in mm. and normally
no provision remains to read the readings with fractions of mm., the present system
while making use of such conventional U-tube manometer takes care of such
limitations and provides for better readability of the measurement. Moreover, the
human error due to parallax is also taken care of by the present system.
In the present system the scale is adapted with facilities to slide with means for
controlled sliding. The dial gauge is preferably mounted with the frame and plate
fixed with the scale is adapted to pulse the plunger of the dial gauge. Such slidable
provision while on one hand enables the initial reading of the dial gauge, when a
reading with factional mm. is required it can be slided and accordingly, the further
precise reading in the dial gauge changes. Such displacement of the scale required
to marking in the scale is obtained from the difference of the two readings of the dial
gauge. An overall accuracy of +/- 0.1mm wc is thus very easily achieved using the
above system of the invention.
Brief description of the accompanying figures
The details of the invention, its object and advantages are explained hereunder in
greater detail in relation to non-limiting exemplary illustrations of the system and its
accompanying gadgets as per the following accompanying figures:

Figure 1: is an illustration of the base plate used in the system of the invention;
Figure 2 is an illustration of the vertical mounting frame used in the system of the
invention;
Figure 3: shows the graduated sliding scale provided in the measurement system of
the invention;
Figure 4: is an illustration of the dial gauge used in the measurement system of the
invention:
Figure 5: is an illustration of the glass U-tube in the system of measurement
according to the invention; and
Figure 6 : is an illustration of the magnifier with sliding element used in the system
of the invention
Reference is first invited to Figure 1, which shows the metallic heavy base (BA) with
adjustable tripods (TP) and also having a round spirit level indicator means (SL).
As shown in Figure 2 the frame is mounted on the stand and a graduated sliding
scale is mounted on the frame as further illustrated in Figure 3. As would be
apparent in Figure 3 the scale is given a facility to slide guided by step screws (SS).
The controlled sliding is achieving by the screw arrangement (SA) attached to the
clamps with the scale and clamps with frame.
Reference is now invited to accompanying Figure 4, which shows the mounting of
the dial gauge (DG) with respect to the frame. As further illustrated in Figure 4 a
plate (PL) fixed with the scale is adapted to pulse the plunger of the dial gauge
(DG). The initial reading of the dial gauge is readily noted. Thereafter, when a
reading with a fractional mm. has to be taken, the scale is slided with the help of the
screw and accordingly, the reading in the dial gauge changes. The displacement of
the scale required to reach the next marking in the scale is obtained from the
difference of two readings in the dial gauge. As the dial gauge is having a least
count of 0.01mm and error is out of the order of 0.02mm. The scale is also provided

with the same order of accuracy and, therefore, an overall accuracy of +/- 0.1mm
wc is very easily achieved using the above system of the invention.
Figure 5 illustrates the glass U-tube mounted on frame above the scale while the
provision of magnifier(MG) with sliding arrangement to read the water meniscus
level on scale is shown in figure 6.
In accordance with the further aspect of the invention the measurement system can
include scale selected with 5 mm. graduation adapted to reduce strain on eyes. The
sliding arrangement can also be made more user friendly by providing set of level
gears and screws with fine threads. Importantly, the readability can be further
improved by using eye piece with crosswire as used in traveling microscope in place
of the magnifier(MG).
Advantageously, it is also possible to use a single tube manometer, which can be
used as a basic gadget such that the pressure reading could be obtained from a
single limb. In such case multiplication factor equal to the ratio of cross section of
manometer tube limb and liquid pod would be applicable.
It would be thus evident that the measurement system of the invention is developed
to include basic principles and the traceability can be established from simple
dimensional measurement. Use of dial gauge for measurement of displacement of
scale is found to be most effective part of the system, which provides for the desired
good accuracy and repeatability with possibility of simple and easy calibration in any
laboratory of dimensional measurement Advantageously, also the magnifier use of
the system with longitudinal scratch avoids parallax error and at the same time
achieves the required magnification of the scale markings. This provides for extra
facility for the user and also ensures desired reliability. The light mounted on the
magnifier is adapted for greater illumination on the scale compared to surroundings
acts as facilitator for operator.
It is thus possible to provide for micro manometer system for the measurement of
ultra low gauge / differential pressure with the accuracy of +/- 0.1mm wc.-or better
wherein the reading from the system would be stable and repeatable and thus
reliable and convenient for the end user Importantly, in the micro manometer

system for the measurement of ultra low gauge / differential pressure the calibration
traceability of the device could be easily established. The system is advantageously
adapted user friendly and ready readability features to favour wide scale application
and use of the system for the measurement of ultra low gauge / differential
pressure.

WE CLAIM:
1 A micro manometer system for the measurement of ultralow gauge/differential
pressure comprising
a base with height adjusting means,
a frame vertically disposed with respect to said base;
a graduated and slidable scale mounted on the said frame;
a dial-gauge mounted on the frame with a tube manometer preferably selected
form glass U-tube manometer and single tube manometer requiring multiplication
factor equal to the ratio of cross sections of manometer tube limb and the liquid pot
mounted on the frame above said scale;

a plate means fixed to the scale adapted to pulse the plunger of the dial gauge such
that apart from the initial reading of the dial gauge for reading with fractional mm
the scale is slide to obtain the next reading;
said dial gauge providing for measurement of displacement of scale accurately and
repeatably
2. A micro manometer system as claimed in claim 1 comprising
a readability improving means preferably selected from a magnifier with sliding
arrangement adapted to read the water meniscus level on the scale and eye piece
with crosswire.
3 A micro manometer system for the measurement of ultralow gauge/differential
pressure as claimed in claim 2 wherein the magnifier with longitudinal scratch
provides for avoiding parallax error and at the same time achieve desired
magnification of the scale.

4 A micro manometer system for the measurement of ultralow gauge/differential
pressure as claimed in anyone of claims 1 to 3 comprising light means mounted on
the magnifier for extra illumination.
5. A micro manometer system for the measurement of ultralow gauge/differential
pressure as claimed in anyone of claims 1 to 4 wherein said means is slidable with
respect to guide means preferably step screws.
6. A micro manometer system for the measurement of ultralow gauge/differential
pressure as claimed in claim 5 wherein for said controlled sliding the screw
arrangement is attached to the clamps with said scale and the clamp with frame.
7. A micro manometer system for the measurement of ultralow gauge/differential
pressure as claimed in anyone of claims 1 to 6 adapted such that the displacement
in the scale required to reach a next marking is based on the difference in the two
readings in the dial gauge and preferably the scale is selected with 5 mm
graduation.
8 A micro manometer system for the measurement of ultralow gauge/differential
pressure as claimed in anyone of claims 1 to 7 wherein the scale sliding
arrangement comprises set of gears and screws with very fine threads.

ABSTRACT

TITLE: A MICRO MANOMETER SYSTEM FOR MEASUREMENT OF ULTRA LOW GAUGE /
DIFFERENTIAL PRESSURE.
A micro manometer system for the measurement of ultra low gauge /differential
pressure, which would achieve an accuracy of +/- 0.1mm. wc or better.Advantageously,
the micro manometer system of the invention is adapted to provide readings, which
would be stable and repeatable and hence reliable for such measurements. Importantly,
the micro manometer system includes a graduated and slidable scale, a dial-gauge
mounted on the frame with a tube manometer preferably selected form glass U-tube and
single tube manometer requiring multiplication factor equal to the ratio of cross sections
of manometer tube limb and the liquid pot mounted on the frame above said scale and a
plate means fixed to the scale adapted to pulse the plunger of the dial gauge adapted for
desired readings. A magnifier with scratch mark favour ease of accurate reading
avoiding parallax and thus having wide scale acceptability and use of such micro
manometer system for the measurement of ultra low gauge / differential pressure.