dead weight piston gauge

1. Koya university
Faculty of Eng.
School of chemical & Pet. Eng.
Pet. Department
Fluid mechanics
EXP. NO. 1
Dead-weight piston gauge
Instructor: mr.pshtiwan
Student name: bayar taher
Experiment contacted on: 1/11/2015
Report submitted on: 8/11/2015
Group: C

2. Aim of experiment
The objective of this experiment is to
calibrate the Bourdon gauge, which is used
to measure gauge pressure.

3. introduction
Dead-Weight pressure Gauge is used for
checking and adjusting pressure gauges.
The pressure is applied via weights which
are placed on a weight support. The latter
has a piston which acts on hydraulic oil in a
pipe system, so that a pressure gauge
which is also connected to the system
should indicate certain pressures.
The device contains a Bourdon gauge with
a transparent dial. The display mechanism
and the various adjustment opportunities
are therefore clearly identifiable.
-Hydraulic oil is used to transfer pressure.

4. theory
Variation in a pressure sensor reading may be calibrated, using
known pressures, to give a gauge reading in engineering units.
As has been seen in exercise A, the dead-weight calibrator
produces a known reference pressure by applying a mass to a
column of fluid. The pressure produced is where 𝐹𝑎 = 𝑚𝑔
-Fa is the force applied to the liquid in the calibrator cylinder.
-M is the total mass (including that of the piston)
-g is the acceleration due to gravity
𝑷𝒂𝒄𝒕. =
𝑭
𝑨
𝑨 = 𝝅𝒓 𝟐
A is the area of piston.
The device for calibrating pressure gauges essentially consist of
two units:
1-The pressure gauge unit, this is where the device needs to be
calibrated and loads are measured with units from the boudon
gauge.
2-The load unit, this is the part where standard weight are
loaded and measured in the pressure gauge unit, the higher the
weights the more pressure it reads, the pressure is transferred
via oil filled line.

5. The layout unit
The following sectional drawing shows load unit and
pressure gauge unit are connected as you can see, both units
are connected by means of a pipeline. When the support is
loaded with weights, the oil pressure in the system increases.
The seal between the piston and the cylinder is metallic, with
no other sealing element. The fit has been very carefully
designed to ensure that the piston operates almost entirely
without friction and with minimal oil leakage. The weights
are designed in such a way that pressure increments of 0.5
bar are possible Place the small weight on the weight
support first. Load and pressure measurement unit are
connected to each other via a pipe, when the piston is
loaded the pressure in the system rises and acts against the
spring on the manometer.

6. procedure
- Open the overflow valve
- Remove the transport-cap
- If necessary topping up the hydraulic oil
- Inserting the piston
-To check the zero point of Bourdon gauge,
proceeds follows:
1-Press the piston out of the cylinder
using the hand wheel.

7. 2-Remove the piston and weight
support.
• 3-Adjust the oil level in the open
cylinder until the cylinder is filled
up to the edge.

8. -After the zero point of Bourdon gauge has been
checked, the weight support is re-inserted into
the cylinder of the pressure gauge unit. The
piston is then slowly lowered by unscrewing the
counterbalance cylinder until it is freely
suspended.
-In order to avoid static friction, set the weight
support in gentle rotation. The mass of the
support is 385 g. Taking into account the piston
diameter of 12 mm, it is now possible to read the
increase in pressure from Bourdon gauge.
-Other pressures occurring when the weight on
the support is increased can be calculated in
exactly the same way. The display of 0.5 bar is
achieved by placing a weight with a mass of 193
g on the support. The other weights weigh 578 g,
which is equivalent to a pressure increase of 0.5
bar each time.

9. calculation
Table of reading
NO m(kg) Pm(bar)
1
2
3
4
5

10. Table of calculating
NO Pm(bar) Pact (bar)
1
2
3
4
5

11. Conclusion
1-The purpose of the Calibration curve is used to determine the
accuracy of the instrument and to ensure that readings from an
instrument are consistent with other instruments.
2-A calibration curve is the graphic or mathematic relationship
between the readings obtained in a process and the theoretical
value in a calibration. The relationship is often established as a
straight line rather than a curve.