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PNEUMATIC ACTUATOR SIZING To
use the Actuator Sizing Table below, the following
information is required:
-
Required maximum valve (load) thrust
in pounds (T)
-
Required valve (load) stroke in
inches. (S)
-
Minimum air (oil pressure for hydraulic
actuator) supply pressure in psi. (P).
-
For spring return actuator, the thrust value
should be multiplied by approximately 2.8 to 3.0 times
before using the table below. This is because, apart
from providing the required valve thrust, the air supply
should furnish sufficient force to overcome the initial
spring-preload force and the force to compress the spring.
Thus, a spring return actuator will have a bore
approximately 70% larger than its double acting equivalent.
Because of the variation of available thrust values
during the actuator stroke, it is possible to optimize the
spring size based on the specific load profile required.
Consult kanair for details.
The valve thrust and stroke can be obtained
from the valve manufacturer. If the actuator is retrofitted
on an existing valve, these values can be measured and/or
estimated reasonable accuracy by knowing the valve
parameters, valve size and the differential pressure across
the valve. Consult Kanair for details.
LINEAR PNEUMATIC ACTUATOR SIZING |
|
MODEL NO. |
BORE (inch) |
ACTUATOR THRUST FOR VARIOUS
PRESSURES |
|
AIR SUPPLY PRESSURE IN psi |
|
40 |
60 |
80 |
100 |
120 |
|
PL 2.5 x * - DA |
2.5 |
184 |
276 |
368 |
460 |
552 |
|
PL 3.25 x * - DA |
3.25 |
300 |
451 |
601 |
751 |
901 |
|
PL 4 x * - DA |
4 |
471 |
707 |
942 |
1,178 |
1,414 |
|
PL 5 x * - DA |
5 |
754 |
1,131 |
1,508 |
1,885 |
2,262 |
|
PL 6 x * - DA |
6 |
1,072 |
1,607 |
2,143 |
2,679 |
3,215 |
|
PL 8 x * - DA |
8 |
1,951 |
2,927 |
3,902 |
4,878 |
5,854 |
|
PL 10 x * - DA |
10 |
3,045 |
4,568 |
6,091 |
7,613 |
9,136 |
|
PL 12 x * - DA |
12 |
4,398 |
6,597 |
8,796 |
10,996 |
13,195 |
|
PL 14 x * - DA |
14 |
5,961 |
8,942 |
11,922 |
14,903 |
17,884 |
|
PL 16 x * - DA |
16 |
7,846 |
11,769 |
15,692 |
19,615 |
23,538 |
|
PL 18 x * - DA |
18 |
9,982 |
14,974 |
19,965 |
24,956 |
29,947 |
|
PL 20 x * - DA |
20 |
12,284 |
18,425 |
24,567 |
30,709 |
36,851 |
|
PL 22 x * - DA |
22 |
14,923 |
22,384 |
29,845 |
37,307 |
44,768 |
|
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* above denotes the valve stroke (minimum cylinder stroke
required)
Example:
Double Acting
Actuator
|
Required Valve Thrust , T............................... |
= |
3,500 lbs. |
|
Safety Factor Used....................................... |
= |
25% |
|
Thrust Value for Actuator Sizing
(1,25 x 3500).... |
= |
4,375 lbs. |
|
Minimum Air Pressure
Available.......................... |
= |
80 psig |
|
From Table I, Cylinder Bore
Required.................. |
= |
10" ( 10" bore actuator provides
6,091 lbs thrust at 80 psig |
|
Valve Stroke Required (say, for 6" gate valve).... |
= |
7.5" |
|
ACTUATOR MODEL
SELECTED..................... |
= |
PL 10 x 08-DA |
Example:
Spring Return
(say, Spring to Close) actuator
|
Required Valve Thrust , T (say)........................ |
= |
3,500 lbs. |
|
Safety Factor
Used........................................ |
= |
25% |
|
Thrust Value for Actuator Sizing
(1,25 x 3500).... |
= |
4,375 lbs. |
|
Thrust for Sizing Spring Cylinder =(3 x 4375) |
= |
13125 lbs. |
|
Minimum Air Pressure
Available.......................... |
= |
80 psig |
|
From Table I, Cylinder Bore
Required................. |
= |
16" ( 16" bore actuator provides
15,692 lbs thrust at 80 psig |
|
Valve Stroke Required (say, for 6"
gate valve)..... |
= |
7.5" |
|
SPRING RETURN
ACTUATOR MODEL SELECTED..... |
= |
PL 16 x 08-SRC |
|
Note: Spring return actuator can be
optimized by adjusting the spring rate or by evaluating the
required thrust as a function of valve stroke. Consult
Kanair for more details. |
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