Blower packages get simplified test code

BL 5389 standard provides wire-to-air performance test for air tubrocompressors.

By Rick Stasyshan and the CAGI Blower Section

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Blower manufacturers offer packaged centrifugal compressors and blowers in both a serial-production manner and made to order. The blower package is fitted with all of the necessary ancillary devices for operation and is marketed as a standard offering by manufacturers.

Existing test codes provide for detailed measurement of the core, or bare blower, but no test standard was available to measure a blower’s package performance; therefore, the Compressed Air and Gas Institute (CAGI) took on the task of developing supplementary codes referencing the existing flange to flange blower — compressor codes ISO 1217 and ISO 5389. The industry and the users of blowers needed a standard method of rating performance of the entire package. This provides users with relevant, accurate information regarding performance of the entire package, true wire-to-air performance.

The development of a standard for measuring package performance in the blower industry builds on work that was done with compressor standards many years ago. The result is a simplified test code for the many types of dynamic blowers along with a standardized performance reporting data sheet template.

White paper: Understanding the CAGI BL 5389 standard
This standard provides a simplified, wire-to-air performance test applicable to a packaged atmospheric air turbocompressor.

CAGI BL 5389: Simplified Acceptance Test of Electric Driven, Low Pressure Turbocompressor Air Blower Package, is a standard that provides a simplified, wire-to-air performance test applicable to a packaged atmospheric air turbocompressor.

This code was developed as part of a broader standard that addresses all types of blowers and as an Annex (G) to ISO 5389, Turbocompressors — Performance test code, Second edition, 2005-12-15. The existing code was simplified to account for the lack of interstage cooling.

The turbocompressor package is defined as a blower with an electric motor drive: direct, geared, or gearless. The drive can be via a conventional electric motor, with or without an inverter, or by a high-speed motor with an inverter. The inverter can be integrated into the package or shipped loose.

Within the criteria of the existing packaged compressor test standard (ISO 5389, E.5.2.b) the definitions of limits to a moderate pressure ratio (≤ 3) and an adherence to Table E.1 for ideal gas behavior, the compression process of the package is considered isentropic — adiabatic and reversible. The compressibility factor (Z) of the air in this range is equal to 1.

To simplify calculations and the test procedure, corrections for Reynolds number and Mach number are considered negligible. This is accomplished by holding that predicted and measured impeller speed should be within 3%.

A standardized data sheet is developed for fixed speed and variable speed packages. The manufacturer provides the flow and specific power to achieve the stated flow at pressure increments of 2 psig.

The possibility for a Class A test (data sheet performance verification) and Class B test (client specified performance verification) is also provided.

BL5389 data sheet

A sample data sheet for a standard packaged high-speed-turbo blower package reported delivered volume flow of the machine and the corresponding specific power for the stated operating speed (Figure 1).

bl 5389 1
Figure 1. A sample data sheet shows delivered volume flow of the machine and the corresponding specific power for the stated operating speed. CLICK TO ENLARGE THE IMAGE

The information in the data sheet is can also be expressed as a chart (Figure 2).

bl 5389 2
Figure 2. The sample sheet data can be represented as a chart.

The stated performance is the volume flow and specific power at site conditions of 14.7 psia, 68 °F and 36% rh.

The test holds a positive 4% tolerance on work and volume. This means that the machine may produce 4% more air than predicted when it is tested. It follows that 4% more work would be needed to compress the air.

A ±4% tolerance on specific power is used. This is a practice followed in other industry test standards and allows for the normal variability of manufacturing.

Testing

CAGI
The Compressed Air and Gas Institute is the united voice of the compressed air industry, serving as the unbiased authority on technical, educational, promotional, and other matters that affect the compressed air and gas equipment suppliers and their customers. CAGI educational resources include e-learning coursework on the SmartSite, selection guides, videos, and the Compressed Air & Gas Handbook. For more information, visit www.cagi.org.

Class A — Data sheet performance verification: The objective of testing is to confirm that the stated performance of a manufacturer’s standard package meets the published performance on each of the tabulated points.

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