Hundreds of thousands of pneumatic actuators used in cement and other industries consume large amounts of compressed air and electrical energy. This document describes the design, testing, and implementation of a pneumatic actuator power saver attachment. The power saver stores compressed air from the return stroke of an actuator in a reservoir, then uses this stored air to power the next return stroke instead of venting it. Testing showed the power saver achieved 49.16% savings in compressed air usage and 47.36% savings in electrical energy consumption. The power saver was successfully installed on a pneumatic actuator in a cement plant.

1. POWER SAVER ATTACHMENT FOR PNEUMATIALLY
OPERAING ACTUATORS(CONCEPT TO COMMISSIONING)
Hundreds of thousands of pneumatically operating actuators run in in cement and other
industries twentyfour hours a day around the world.These actuators consume an
extremely large quantity of compressed air that was produced equally using very high
quantum of electrical energy,The electrical energy is not only a high cost commodity
,but is produced at the cost of our environmental health.Therefore it is absolutely
essential for the users of compressed air to honestly exercise a control on the use of this
high cost commodity and ensure that any wastage is plugged off.They should also make a
sincere effort on a consistant basis to improve the productivity of the compressed air they
use as a regular agenda and not an one time task.
In the present scenario of industrial practice,it is considered to be absolutely normal that a
pneumatically operating actuator in any industry will vent out expensive compressed air
into the atmosphere during every stroke which is not only a high loss of energy but is also
a noise pollutant.Although suppliers provide silencers in the exhaust ports of solenoid
operated block valves but the same is insufficient to efficiently plug off noise
pollusion.Since the number of these actuators in various industideries is very very high
when considered globally,the enomous watage of electrical energy can very well be
appreciated.
Motivated by the observation of such huge loss which is otherwise considered to be
absolutely normal,a sincere effort was made to study the whole aspect and find out ways
and means to minimize this huge loss.During trials,it was observed that the actuators
need compressed air at higher pressure during it’s power strokes and lower pressure
during it’s return strokes.Inspite of this fact,the actuators are fed with common
compressed air reservoir supplying compressed air at high pressure during both power
and return strokes of the actuators.
Motivated by the above facts as a result of observation and basis for the project,a system
was conceptualized,designed,fabricated and extensive trials were conducted.The
following diagram illustrates the system designed.

2. Pneumatic Actuator Power Saver Design
LOAD

3. How the system works:
Sequence of operation:
1. Air from compressor is supplied to solenoid valve(SV1) through inlet port.
2. Compressed air goes into piston end chamber of pneumatic cylinder through service
port A of solenoid valve(SV1).Service port B of solenoid valve(SV1) is dummied
permanently.
3. Piston starts moving forward.
4. Compressed air from rod end of cylinder starts coming out and the same is stored in
reservoir(RES1)
5. Piston of cylinder(NC1) completes its forward stroke and reaches it’s extreme end.
6. Service port A of solenoid valve(SV1) closes after it gets electrical feed back to start
return stroke.Simulteneously,exhaust of solenoid valve(SV1) opens to atmosphere.
7. Compressed air saved in reservoir(RES1) during previous stroke starts pushing the
piston backward.Compressed air piston end chamber of cylinder(NC1) is released to
atmosphere through exhaust port of solenoid valve(SV1).This way,return stroke of the
piston is completed.
8. The cycle(Forward and return stroke) thus operates number of times by consuming air
from compressor only for forward stroke and reusing waste air for actuation of return
stroke which otherwise is wasted into the atmosphere conventionally.
9.After couple of operating cycles, air pressure drops in reservoir((RES1) bellow a preset
limit that is not sufficient for actuation of return stroke of piston.
10. At this point, low pressure in reservoir(RES1) opens solenoid valve(SV2) through
pressure switch(PS1).Air from compressor is supplied to reservoir(RES1) through
solenoid valve(SV2),NRV and the orifice.
11. The moment,the pressure in reservoir(RES1) increases to a preset value, solenoid
valve(SV2) closes through feed back from pressure switch(PS1) and air supply from
compressor to reservoir(RES1) is cut off.The make up compressed air volume, thus
consumed is minimal.
12. The cycle thus continues.
Trial results:
Compressor specification:
Type-Reciprocating
Motor KW- 7.5
Pressure setting:
Compressor starts at 4.5 kg/cm sq
Compressor stops at 5.0 kg/cm sq
Connected load- A pneumatic cylinder with load was operated with the compressor.

4. Trial 1:
Cylinder was operated without use of power saver for 4 hours with a preset timer arrangement.
The cylinder consumed 29492 list of compressed air.
Therefore air consumption is 7.373 cu mar/hr
Avgas power consumption recorded as 1.9 kHz(As shown in table bellow)
Therefore,1 cu mtr of air will consume 0.257 kwh of power
Trial 2:
Cylinder was operated with the use of power saver for 4 hours with a preset timer arrangement.
The cylinder consumed 14996 lits of compressed air.
Air consumption by cylinder was found to be 3.749 cu mtr/hr
Therefore, by using power saver, saving in air consumption is 7.375 cu mtr/hr -3.749 cu mtr/hr = 3.626 cu mtr/hr
Therefore,Percentage of saving in air by using power saver is
7.375 cu mtr of air- saving is 3.626 cu mtr of air
Therefore, In 1 cu mtr of air- saving will be 3.626 cu mtr/7.375 cu mtr
Therefore, In 100 cu mtr of air- saving will be 3.626/7.375*100 = 49.16%
KWH READINGS OF COMPRESSOR DURING TRIALS
MOTOR RATING
RUNNIN
G HOUR
FIRST
READING
LAST
READING
KWH
KWH/HOUR
TOTAL
RUNNING
REMARKS
KW VOLTS AMPS RPM
7.5 415 14 1430 4 HR 0 7.59 7.59 1.9 4 HR
Actuator
without
power saver
4 HR 0 4.01 4.01 1 4 HR
Actuator
with power
saver
As per above test result sheet,
Saving in power by using power saver= 1.9 kwh-1 kwh= 0.9 kwh
Now, I.9 kwh saving is 0.9 kwh
In 1 kwh, saving will be 0.9/1.9
Therefore, in 100 kwh, saving will be 0.9/1.9*100= 47.36%
Therefore, saving in power by using power saver,Power saving will be 47.36%

5. nstallation and commissioning:
Following photograph illustrate actuator operating with power saver
The power saver was installed in one of feed hopper gate of rotary packer machine in a
cement plant as illustrated in above photographs..
Same saving in compressed air and power was acheved as that in lab trial runs.
Conclusion:
By using power saver,we achieve 49.16% saving in compressed air consumption
and 47.36% in electrical energy consumption

6. Needless to mention that saving in electrical energy will be directly proportional to the
number of strokes per unit of time and also the volume of the actuator.
It is hoped that the users of the pneumatic actuators will give a fair trial to adopt this
system and help the world community to enjoy a better tomorrow.
THE END

7. Needless to mention that saving in electrical energy will be directly proportional to the
number of strokes per unit of time and also the volume of the actuator.
It is hoped that the users of the pneumatic actuators will give a fair trial to adopt this
system and help the world community to enjoy a better tomorrow.
THE END