USE OM - JANUARY 2017
56
be a first order equation with respect to the calculated air flow rate. This
is not an iterative process.
C
nz
= 1 + (
A
+
BQ
s
)
*
B
SH
/ 100
K6
Where;
A
= intercept constant from first order trend line
B
= slope constant from first order trend line
C
nz
= nozzle correction factor
5.1.6.2.2.3
If the first order trend line does not reasonably match the
data (R
2
< 0.5) then a repeat of Section 5.1.4 shall be required.
If the retest demonstrates that the data is not repeatable (any retested
point more than 1% different from the previously tested point) then the
nozzle combination is disallowed from rating tests. Other combinations
can be qualified to cover the disqualified range of air flows. No Laboratory
Certification Tests shall be performed with a disqualified or un-calibrated
nozzle combination.
5.1.6.2.2.4
The instrument inducted latent capacity shall be
calculated using ASHRAE 37 - 2005 Section 7.3.3.1. The value shall be
reported and the Instrument Induced Latent/Sensible Capacity Ratio shall
be calculated, L/S, and reported as a percentage. If this ratio exceeds
5% an investigation into the humidity measurement error should take
place.
5.1.6.2.2.5
No correction, either single or equations will be allowed
that exceeds a 4% correction. Nozzle combinations that have a
B
SH
greater than 4.0% shall not be used during Laboratory Certification Tests
5.1.6.2.3
Corrective actions such as adding baffles, replacement or rearrangement
of nozzles, or correction of instrumentation problems are acceptable practices. Any
modification requires that Section 5.1.4 tests be re-run for all nozzle combinations and
the analysis in this section be performed on the new test data.
5.1.6.2.4
For the test where half of the heater banks is turned off and half is turned
on, any of the nine (9) grid thermocouples shall meet the following criteria (refer to
ASHRAE Standard 116 Section 7.4.3.4.2):
t
g(1-9)
=
t
gaverage
+/- 0.75 °F
K7
5.1.6.2.5
For all Laboratory Certification Tests, air flow rates used in all calculations
shall be with
Q
SC
substituted in place of
Q
s
or
Q
mi
, as appropriate.
𝑄
𝑚𝑖
= (𝐶
𝑛𝑧
∗ 𝐶) ∗ 𝐴
𝑛
∗ √2𝑃
𝑉
𝑣
′
𝑛
K8
[
= 775.9(𝐶
𝑛𝑧
∗ 𝐶) ∗ 𝐴
𝑛
√2𝑃
𝑉
𝑣′
𝑛
= 1097(𝐶
𝑛𝑧
∗ 𝐶) ∗ 𝐴
𝑛
√𝑃
𝑉
𝑣′
𝑛
]
Q
SC
=
Q
S
*
C
nz
K9
or
Q
SC
=
Q
mi
*
C
nz
K10
