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Types of Testing |
Air performance testing using AMCA Standard 210, ANSI/ASHRAE Standard 51
Air testing is performed using test chambers designed per AMCA standard 210.
During these tests, airflow, pressure, RPM, and fan input power are measured at
various operating points. Static pressure can be adjusted during the test by the
use of an exhaust or supply fan along with a damper. This setup allows the fan performance
to be measured over its full range. Airflow is determined by measuring the differential
pressure across flow nozzles. Static pressures are measured in chambers that have
relatively large areas, which reduce velocities and ensure accurate and repeatable
readings. Data is gathered by a data acquisition system that records and displays
real time results. |
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For new product certification (air and sound), data collected in our laboratory
can be submitted along with the proper forms and test configuration information
to AMCA. This submittal follows steps outlined by AMCA’s Certified Ratings
Program. For more information about AMCA’s Certified Ratings Program, click
here.
A recently added high-pressure chamber is capable of testing static pressures up
to 80 in.-w.g. This chamber can be orientated for Figure 12 or Figure 15 testing.
The high-pressure chamber is also advantageous for testing small, low flow fans,
as the leak rate of the high-pressure chamber is many magnitudes lower than that
of a larger more typical chamber. TCFC also has a “large” Figure 12
chamber and a “large” Figure 15 chamber with flow measurement capacities
over 60,000 CFM each.
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Data acquisition system and controls for air
performance testing on "large chambers"
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A TCFC fan is air performance tested
in the lab's large Figure 12 chamber
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A roof ventilator is mounted
on the high-pressure chamber
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Capacities of TCFC test chambers are as shown below: |
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* The combined length of the fan plus the duct limit applies
to sound testing only. |
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Sound testing using AMCA Standard 300 |
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Our customers are provided with sound power level data developed from product testing.
To keep our data current we test new fan designs as well as retest our established
product lines. All sound data certified since our 1993 addition of the semi-reverberant
room is based on test data from our AMCA accredited laboratory and verified by AMCA
as required per AMCA Publication 311 (Certified Sound Ratings Program for Air Moving
Devices). Sound data certified prior to our 1993 addition was tested at AMCA. |
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Microphone boom with travel
as required per AMCA Standard 300
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Our sound testing is performed in a semi-reverberant room using the substitution
method. In this method, sound pressure levels of a reference sound source,
with known sound power levels, are measured. The relationship between measured
pressure levels and known power levels is used to determine the room characteristics.
This is performed before each fan sound test, since variables such as ambient conditions
and fan location, can change the room characteristics. The sound power levels of
a fan are then determined by measuring its sound pressure levels and adjusting for
room characteristics as determined by the substitution method described above. This
approach is used by AMCA to establish a uniform testing procedure for laboratories
that is both accurate and practical.
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B & K 2133 analog frequency analyzer
and NI digital sound measurement system
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Silencers allow flow into and out of
the sound room while minimizing noise
entrance from other parts of the lab
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Jet fan thrust testing using proposed AMCA 250 draft
For certain applications, fans are specified by the amount of thrust they produce
rather than a typical flow vs. pressure specification. Fans for these applications
are known as jet fans. TCFC has constructed a test rig per the proposed AMCA 250
draft. For this type of testing, a fan is suspended in a manner that leaves it free
to move axially except where restrained by a load cell. When the fan is operated,
the fan is adjusted back to its level position by adjusting the connection to the
load cell, allowing the load cell to measure the full thrust of the fan. Using current
lab equipment in order to comply with the requirements of AMCA Standard 250, the
test lab is limited by the following maximum values:
* Any thrust greater than 500 lbf. may require
test rig modifications
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Jet fan test setup in TCFC laboratory |
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Note: It is possible to exceed some of the limitations above to perform a test,
however, that test will not meet all of the requirements stated in the AMCA standards.
If the 50 HP limitation on both chambers needs to be increased for a test, a generator
needs to be rented that will be able to power the motor. Additionally, all parts
required for the test must fit through our 95" x 110" delivery door. |
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Static and dynamic strain testing
When new products are developed, rotational speed limits of the impeller need to
be determined and verified as valid. To determine these limits, computer models
are generated and analyzed using Finite Element Analysis (FEA). Strain gages can
then be placed on fans in the high stress areas determined by FEA and engineering
judgment to verify the accuracy of the computer models. The signals from these gages
are transmitted through slip rings so the strains are recorded while the fan is
running. Speeds and operating points can be changed while monitoring the strains
to simulate worst case conditions. Both static and dynamic strains can be recorded. |
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Vibration testing and modal analysis
Complete fan assemblies may need to be analyzed for structural rigidity. This is
performed by vibration measurements at various speeds. A number of diagnostic tools
including balancers, spectrum analyzers, and modal analysis equipment are used.
Vibration testing and modal analysis is also useful for field diagnostics. |
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Modal analysis setup on high inertial mounting base |
Endurance testing
In addition to FEA and strain testing, some products are cycle tested for long periods
in order to analyze wear patterns and any indications of fatigue that may develop.
Based on these tests, products are improved and retested to ensure that our customers
will only receive fans that provide a long life without failure. |
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Safety testing
TCFC has recently become a member of UL’s Client Test Data Program (CTDP).
Being a member of the CTDP means that UL has audited and witnessed testing in TCFC’s
test lab and verified that the procedures and methods used by technicians and engineers
in TCFC’s lab conform to UL standards. Requirements and calibration standards
of test equipment are audited per project in the CTDP as well. UL accepts test data
submitted by CTDP members as if it were tested by UL. TCFC is recognized in the
CTDP for testing to UL 705 and CSA 22.2 No. 100 and 113. These standards cover safety
testing, such as motor temperature rise testing, abnormal or extreme (under/over)
voltage testing, rain testing, and dielectric voltage-withstand testing. The majority
of testing monitors motor temperatures and current draw to verify safe operation
of the test units in various field conditions, including unfavorable and extreme
conditions. TCFC’s safety testing laboratory is equipped with an automated
data acquisition system allowing for multiple units to be tested simultaneously
with data scans at any interval required. Data is plotted on a computer monitor
during testing and is also recorded numerically. Numerical data is then reduced,
organized, and labeled using a TCFC program and can then be submitted to UL. |
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Roof
ventilators are mounted on test
stands in TCFC's safety (UL) test lab |
Temperature
data as scanned by the data
acquisition and shown on a computer monitor |
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Copyright © 2011 Twin City Fan Companies, Ltd. |
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