thePetroStreet

Guys, can any one share the difference between the type I & type II of ASME PTC-10?

According to PTC-10, type 1 tests are conducted with the specified gas at or near the specified operating conditions. Allowable deviations in the specified gas and operating conditions must be followed as mentioned in the table 3.1 of the code. These limitations imposed in table 3.1 are subjected to further restriction that their individual or combined effects shall not exceed the limits of table 3.2.

Type 2 tests may be conducted by using specified gas or a substitute gas. This type of test follow the limitations imposed in table 3.2 ONLY. The test speed in this test is often different than the specified operating condition speed.

For more details, you may refer to para 3.2 of PTC-10.

irish, can you also explain what would be in table 3.1 and 3.2, as you are referring to those.

Table 3.1 contains the allowable deviations from the operating conditions while conducting test type 1 only like the inlet pressure must not deviate more than 5% of the operating conditions value. Likewise, deviations for inlet temperature, speed, molecular weight, density capacity, cooling temperature difference and coolant flow rate have been mentioned which should be followed during the test.

Table 3.2 includes the allowable deviations from the operating conditions while conducting test type 1 or 2 which are the specific volume ratio, flow coefficient, machine Mach number and machine Reynolds number.

Type 1 test has to follow both the tables while type 2 test has ONLY to follow the limitations imposed in table 3.2 and follow the permissible deviations.

ASME PTC-10 is an extensive document dealing with the testing of centrifugal / axial compressors / exhausters. This document specified two type of test as follows;

• Type I - It covers situations in which process gas and test gas are identical within certain predefined and agreed limitations. So that one runs a near-perfect, full load and full-speed test.
• In some instances, where process gas and actual operation are not viable option during test, there are other possibilities. These include setting up a closed piping loop filled with gas mixture closely approximates the actual process gas. This testing will permit the simulation of actual conditions and can thus be expected to give some information about the likely behavior of machine.

Here are permissible deviations for type I for your reference

Variable Permissible deviation
1. Inlet pressure = 5%
2. Inlet pressure = 8%
3. Speed = 2%
4. Molecular weight = 2%
5. Cooling temperature difference = 5%
6. Coolant flow rate = 3%
7. Capacity = 4%

Permissible fluctuations of test readings For Type I and Type II tests

Measurement Fluctuation
Inlet pressure = 2%
Inlet temperature = 0.50%
Discharge pressure = 2%
Nozzle differential pressure = 2%
Nozzle temperature = 0.50%
Speed = 0.50%
Torque = 1%
Electric motor input = 1%
Mo1. weight = 0.25%
Cooling temperature difference = 0.50%

thanks dexter, any how i think one of the following is temperature;

Variable Permissible deviation
1. Inlet pressure = 5%
2. Inlet pressure = 8%

yeap, its inlet temperature with permissible deviation of 8%.

Hi, I have gone through the correspondance above, could you please let me know the permissible diviations allowed for ASME PTC 10 Type 2 test, which i believe is as per table 3.2?

Hi Hussain,
As per table 3.2, the permissible deviations are as under:
Specific volume ratio = 95 - 105
Flow co-efficient = 96 - 104
Machine Mach and reynolds number - as per figures 3.3, 3.4 and 3.5
For axial compressors where machine Reynolds number is below 100,000 = 90 -105
For axial compressors where machine Reynolds number is above 100,000 = 10 - 200
The deviations / limits are percents of design values.

hussain, let me re clarify that type II test is not as per actual operating / design conditions. So that is the major deviation. ASME doesn't allow any other deviation in type II tests in particular. The table you are referring to is for the permissible deviations of machine mach number, reynolds numbers and flow coefficient for both types of test. I think you get the point.

Anyhow if you want to know any specific deviation permissible in any of these test types, just let me know.