TAB Journal Fall 2020 - 3

performance from the submittal is shown in the table and
Figure 1 on pg. 4.
The process air was traversed at the discharge duct connecting
to the surgery AHU. The design of 4,000 cubic feet per
minute (CFM) was easily set and confirmed using the traverse
and variable frequency drive. The regen air was more difficult
to confirm because of the configuration of the unit. The intake
had a small rain hood, the discharge was very turbulent with
only louvers on the side of the unit, and the filter bank was
close to the fan discharge. Comparing velocity readings taken
at both the filter bank and in windy conditions at the regen
intake hood yielded airflows ranging from 1,750 - 3,500 CFM.
The humidity leaving the desiccant wheel (C on Figure 1)
was not reaching design, achieving only 42 percent relative
humidity (RH), and thus leaving the process side at over 60
percent. The regen temperature was not at design either; the
regen steam coil was only measuring 195°F. The hospital and
the engineer were convinced the regen airflow was too high.
The desiccant wheel manufacturer's representative suggested
using the pressure drop across the wheel to calculate the airflow
of the regen air. This is the method they use at the factory

to test airflow prior to shipping. The process air measured
pressure drop matched the submittal at 0.72 in. water gauge
(w.g.) and confirmed the duct traverse at 4,000 CFM. The regen
air pressure drop measured 0.28 in. w.g. Per the submittal, the
pressure drop should be 0.55 in. w.g. At design flow, the in. w.g.
calculated to 1,800 CFM, confirming the regen airflow was, in
fact, low. The hospital admitted they had changed the motor
and fan sheaves a few months before to increase the regen
temperature by decreasing the suspected high regen airflow.
The original sheaves were found and replaced. The wheel
pressure drop was retested and now confirmed back up to
0.55 in. w.g. The regen airflow now confirmed at 2,500 CFM.
The regen temperature was still only 188°F versus a design of
213°F and not taking the moisture off the new desiccant wheel.
The steam control valve was removed and found to be only
partially opening. The steam control valve was replaced and
220°F was achieved. The process air was now operating and
testing as designed. The operating rooms quickly recovered by
recording room conditions of 62°F at 50 percent humidity.
Reflecting back on the steps taken to get the desiccant
dehumidification unit back to design conditions; the problem

Fast and Simple Means To Change CFM Accurately

THINK SAFETY
Drill Holster

Diameter Gauge

Functional Vest
Pulley GPS

We Keep You
How It Works



Organized



Using the diameter gauge, read pulley diameter



Safe



For Fixed sheave pulley, use chart to get replacement pulley



Efficient



For Variable Pitch Pulley, use pulley GPS to read the
pulley's operating position, OP (pitch diameter).



Use the chart to get # of turns for desired airflow or



Replacement pulley and the Operating Position



It is that simple.

PI charts are color coded; shows the right size of belt at each operating position
No calculation or tachometer is required to accurately change airflow

TAB
Journal
FallSimple
2020
Fast
and

Means To Change CFM Accurately

You Make More
Money Safely

www.pinstruments.expert
info@pinstruments.expert

THINK SAFETY

3


http://www.pinstruments.expert

TAB Journal Fall 2020

Table of Contents for the Digital Edition of TAB Journal Fall 2020

TAB Journal Fall 2020 - Cover1
TAB Journal Fall 2020 - Cover2
TAB Journal Fall 2020 - 1
TAB Journal Fall 2020 - 2
TAB Journal Fall 2020 - 3
TAB Journal Fall 2020 - 4
TAB Journal Fall 2020 - 5
TAB Journal Fall 2020 - 6
TAB Journal Fall 2020 - 7
TAB Journal Fall 2020 - 8
TAB Journal Fall 2020 - 9
TAB Journal Fall 2020 - 10
TAB Journal Fall 2020 - 11
TAB Journal Fall 2020 - 12
TAB Journal Fall 2020 - 13
TAB Journal Fall 2020 - 14
TAB Journal Fall 2020 - 15
TAB Journal Fall 2020 - 16
TAB Journal Fall 2020 - 17
TAB Journal Fall 2020 - 18
TAB Journal Fall 2020 - 19
TAB Journal Fall 2020 - 20
TAB Journal Fall 2020 - Cover3
TAB Journal Fall 2020 - Cover4
https://www.nxtbook.com/ygsreprints/AABC/tab-journal-winter-2021
https://www.nxtbook.com/ygsreprints/AABC/G122399AABC_Fall2020
https://www.nxtbook.com/ygsreprints/AABC/G120138AABC_Summer2020
https://www.nxtbook.com/ygsreprints/AABC/G118248AABC_Spring2020
https://www.nxtbook.com/ygsreprints/AABC/G116302AABC_Winter2020
https://www.nxtbook.com/ygsreprints/AABC/G114573_AABC_Fall2019
https://www.nxtbook.com/ygsreprints/AABC/G111085_tab_summer2019
https://www.nxtbook.com/ygsreprints/AABC/g108931_tab_spring2019
https://www.nxtbook.com/ygsreprints/AABC/g104992_tab_winter2019
https://www.nxtbook.com/ygsreprints/AABC/g100221_tab_fall2018
https://www.nxtbook.com/ygsreprints/AABC/g97743_tab_summer2018
https://www.nxtbook.com/ygsreprints/AABC/g94804_tab_spring2018
https://www.nxtbook.com/ygsreprints/AABC/g91043_tab_winter2018
https://www.nxtbook.com/ygsreprints/AABC/g86727_tab_fall2017
https://www.nxtbook.com/ygsreprints/AABC/g81312_tab_summer17
https://www.nxtbook.com/ygsreprints/AABC/g78003_tab_spring17
https://www.nxtbook.com/ygsreprints/AABC/g73432_tab_winter17
https://www.nxtbook.com/ygsreprints/AABC/g7002_tba_fall2016
https://www.nxtbook.com/ygsreprints/AABC/g65897_tab_summer2016
https://www.nxtbook.com/ygsreprints/AABC/g62758_tab_spring16
https://www.nxtbook.com/ygsreprints/AABC/tab_winter2016
https://www.nxtbook.com/ygsreprints/AABC/tab_fall2015
https://www.nxtbook.com/ygsreprints/AABC/tab_summer2015
https://www.nxtbook.com/ygsreprints/AABC/g50853_aabc_spring2015
https://www.nxtbook.com/ygsreprints/AABC/g48663_aabc_winter2015
https://www.nxtbook.com/ygsreprints/AABC/g46741_aabc_fall2014
https://www.nxtbook.com/ygsreprints/AABC/g43965_aabc_summer2014
https://www.nxtbook.com/ygsreprints/AABC/g42323_aabc_spring2014
https://www.nxtbook.com/ygsreprints/AABC/g40447_aabc_winter2014
https://www.nxtbook.com/ygsreprints/AABC/g38793_aabc_fall2013
https://www.nxtbook.com/ygsreprints/AABC/g36202_aabc_summer2013
https://www.nxtbook.com/ygsreprints/AABC/g34728_aabc_tabspring2013
https://www.nxtbook.com/ygsreprints/AABC/g32884_aabc_tab-winter2013
https://www.nxtbook.com/ygsreprints/AABC/g30873_aabc_tabjournal_fall2012
https://www.nxtbook.com/ygsreprints/AABC/g28877_aabc_tabjournal_summer2012_2
https://www.nxtbook.com/ygsreprints/AABC/g25452aabc_tabspring12
https://www.nxtbook.com/ygsreprints/AABC/g23327aabc_fall_2011
https://www.nxtbook.com/ygsreprints/AABC/g21694aabc_summer11_final
https://www.nxtbook.com/ygsreprints/AABC/g19912nxtbk
https://www.nxtbook.com/ygsreprints/AABC/g19105_aabc_tabjournalwinter11
https://www.nxtbook.com/ygsreprints/AABC/AABC/p17871_aabc_fall10
https://www.nxtbook.com/ygsreprints/AABC/g16041aabc_tabjournal
https://www.nxtbookmedia.com