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![Page 1: TSI Incorporated – Critical Environments Copyright© 2006 TSI Incorporated Critical Environments Laboratory Control Basics and Room Control Strategies.](https://reader035.fdocument.pub/reader035/viewer/2022062313/56649cff5503460f949cfccb/html5/thumbnails/1.jpg)
Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Critical Environments
Laboratory Control Basics and
Room Control Strategies
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Insert Agenda slide
•Laboratory customers and goals•Laboratory environment
–Safety–Comfort–Experiment integrity–Energy efficiency
•Room pressurization control–Constant Volume–Direct pressure–Flow tracking, a.k.a. “Airflow Tracking” or “Volumetric Offset” –Flow tracking with pressure feedback
•VAV control types–Constant Volume–Direct pressure–Flow tracking, a.k.a. “Airflow Tracking” or “Volumetric Offset” –Flow tracking with pressure feedback
•Temperature control•Laboratory control
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Laboratory Customer Types
• Universities– Teaching labs– Research labs
• High Schools/Middle Schools• Hospitals
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Laboratory Customer Types
• Government Facilities– USDA– FDA– GSA & ATF– CSI
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Laboratory Customer Types
• Industry– Technology companies– Pharmaceutical manufacturers
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Laboratory Goals
• Safety– Containment
• Primary: fume hood containment• Secondary: Directional room airflow-net
negative airflow labs– Ventilation (dilution)
• Comfort– Temperature– Ventilation – Sound
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Laboratory Goals
• Experiment Integrity– Protection of research– Uniform airflow, reduce drafts– Stable room pressurization
• Energy-efficiency– Current energy costs (Q1,2006): $7.50/cfm; 1000 cfm
hood costs $7,500/yr)
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Laboratory Goals
Concerning your past involvement in lab controls:
Has there been any other laboratory goals or needs
that you were asked to address or meet?
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Laboratory Environments
• Use determines Requirements– Animal Research– Clinical labs– Analytical Chemistry– Teaching labs– Biocontainment– Forensic labs– Nanotechnology
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Laboratory Environments
• Ideal laboratory configuration– Designed to meet specific requirements for a given
application or task– Chemical lab will have different needs than a
pharmaceutical lab or vivarium
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Laboratory Safety
• Minimize long-term exposure to chemicals and fumes
• Primary Containment– Fume hood– Laminar flow bench– BSC– Snorkels
• Secondary Containment– Laboratory itself
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Laboratory Safety
Objectives of Lab Ventilation– A laboratory is built to accommodate materials and
processes that contaminate air which may pose a health risk to the occupants
– Lab exhaust devices capture contaminants– Lab exhaust system removes contaminants– Lab ventilation system provides dilution air
• 100% Outside Air (4-12 air changes per hour)
• No Recirculation
• 24 hours/day, 7 days per week
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Laboratory Safety
• Ventilation rate examples– OSHA
• 4-12 ACPH
– Prudent Practices• 6-12 ACPH
– ASHRAE Laboratory Ventilation• 6-10 ACPH
– NFPA• Minimum of 4 ACPH
• Typically greater than 8 ACPH when occupied
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Calculate Air Exchange Rate (ACPH)Air Changes Per Hour
To calculate air exchanges per hour, use the following formula:L= LengthW= WidthH= HeightCF= Cubic Feet (of lab space)ACPH = Air Changes (or exchanges) Per Hour
• Measure your room and work the following equation:L’ x W’ x H’ = CF (ex: 10’ X 12’ X 8’ = 960 CF with 180 cfm)
• 180 cfm / 960 CF = .1875/m• .1875/m x 60m/h = 11.25 ACPH
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Examples of Air Changes per Hour Lab Space ACH OA
Chemistry (standard Wet Lab) 10 100%
Biological (Tissue Culture, DNA) 12 100%
Special Lab (High Odor Generation) 30 100%
Chemical Storage & Distribution 10 100%
Analytical Lab (Instrument Room) 12 100%
Equipment Room (autoclaves, centrifuges, freezers) 15 100%
Computer server or dry electronics lab 12 to 60 20 cfm/person
Animal rooms 15 100%
ISO Class 4 Clean room 660 20 cfm/person
ISO Class 5 Clean room 600 20 cfm/person
ISO Class 6 Clean room 200 20 cfm/person
ISO Class 7 Clean room 70 20 cfm/person
ISO Class 8 Clean room 20 20 cfm/person
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Laboratory Comfort
• Maintain space temperature– More challenging with VAV
• Maintain ventilation– Normally covered by ACPH for a
given lab application– Limit infiltration from sources
other than HVAC system– Reduce drafts or odd airflow
patterns
• Minimize noise
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Experiment Integrity
• Protection of research and personnel is accomplished with:
• Laminar flow bench• BSC• Fume hoods• Chemical storage
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Energy-Efficiency
• Exhaust as little air as possible without impacting safety or comfort– Using less air is the most promising tactic
• VAV system• Occupied and unoccupied modes
– Recover the heat– Move air more efficiently– Increased initial cost– Saves operating expenses in the long-term
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Room Pressurization Control
To maintain directional airflow by controlling supply and exhaust air flows in order to pressurize or depressurize the room relative to an adjacent space and to maintain a comfortable, non-fluctuating air temperature.
• Primary containment– Laboratory fume hoods
– Biological safety cabinets
– Snorkels
• Secondary containment– Laboratory room itself
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Room Control Strategies
• Constant Volume (CV)– Control and/or balance supply & exhaust flows– Monitor pressure only
• Constant Volume (CV) – Two Position– Control and/or balance supply & exhaust flows– Monitor pressure only
• Variable Air Volume (VAV)– Control supply & exhaust flows under varying loads– Monitor critical parameters
NOTE: CV and VAV also used on lab hoodsNOTE: Dampers and flow stations or Venturi valves can be used for either CV or VAV systems
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Constant Volume
• May monitor ΔP• No ΔP Control
– Simple– Read only
• 8635-M• 8610/12,8650-MON• CVV (Venturi Valve)• Temp by others• Requirements
– Closed door– Low Traffic– Stable reference
8650-MON
8635-M
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Constant Volume
• Use Constant Volume when– Low hood density (large room with one hood)– Low concern regarding energy usage– Room ventilation rates of 10 ACPH or more
• Advantages– Easy to design– Minimizes cost of controls– Few controls to maintain
• Disadvantages– Equipment sized for full flows
• High initial and operating costs – Difficulties arise when relocating equipment– Limits future expansion– Wastes energy
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Variable Air Volume (VAV)• Use a Variable Volume System when
– High hood density– If fume hood energy usage exceeds lab ventilation or thermal requirements
• Advantages– Reduced energy costs
• less air conditioned• supplied and exhausted air vary depending on loads
– Use of unoccupied mode with reduced flows saves energy – Applying diversity factors
• Sizing equipment based on expected flows as opposed to maximum flows– Pressure-independent VAV controls adapt to system changes
• Maintain constant face velocity regardless of sash position• Modulate supply and exhaust based on room ΔP or temperature demand
• Disadvantages– Reduced airflows and energy usage are dependent on good hood user sash
position management– Increased HVAC system complexity– Higher installation costs
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
VAV Control Types
• Direct pressure– Measure room pressure differential – Maintain it
• Flow tracking– Measure supply and exhaust air flows– Maintain an offset between supply and exhaust flows
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
VAV Control Types
• Flow tracking with pressure monitoring– Measure supply and exhaust air flows– Monitor pressure differential– Maintain an offset between supply and exhaust flows
• Flow tracking with pressure reset (AOC)– Measure supply and exhaust air flows– Maintain an offset between supply and exhaust flows– Measure pressure differential– Adjust offset between supply and exhaust flows
based on pressure measurement
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
VAV Control Type Features
Direct Pressure Control
Flow Tracking Control
Flow Tracking Control with ΔP
monitoring
Flow Tracking
Control with ΔP
feedback
Measures room ΔP X X X
Modulates supply and exhaust flows X X X X
Measures supply and exhaust flows X X X X
Fixed flow offset X X
Adjusts flow offset to meet room ΔP set point X
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Factors to consider in Determining Control System Strategy
• Number of hoods• Room volume• Energy costs• Room Ventilation Rates• Hours of Operation
(occupied/unoccupied hours)
• Heat generation in labs• Number of researchers• Type of lab work being
performed
• Open or closed lab• Tightness of constructed
envelope• Complexity of cleanliness
requirements• Speed of disturbances and
response• Duct conditions for flow
measurement
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
VAV Control Loops
• Direct pressure – Closed loop on pressure
• Flow tracking – Closed loop on flow
– Open loop on pressure
• Flow tracking with pressure monitoring– Closed loop on flow
– Open loop on pressure
• Flow tracking with room pressure feedback– Closed loop on flow
– Closed loop on pressure
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Open Loop on Pressure – Closed Loop on Flow
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Closed Loop on Pressure – Closed Loop on Flow
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Direct Pressure Control
8650
Model 8636
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Direct Pressure Control
• Measure room pressure differential with thru-the-wall sensor
• Modulate supply and exhaust to maintain room pressure differential set point
• Measure the supply flow to set minimum ventilation rate and to determine ACPH
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Direct Pressure Control
• Closed loop on pressure– Adjusts supply and exhaust to
maintain room pressure differential and reheat
• Easy to implement• Safest
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Direct Pressure Control
• Requirements– Closed door with low traffic– Stable reference
• Fluctuations in reference space will cause disturbances within the lab
– Supply flow measurement is required for ventilation control and to determine ACPH
• TSI Models 8635, 8636
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Direct Pressure Control
• Used In– Labs where containment is
critical
– Small closed labs
– Low cost is key
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Direct Pressure Control
• Most engineers / consultants understand
• Works very well when properly applied
• ΔP guaranteed
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Direct Pressure Control Sequence of Operations
If fume hood flow increases and makes space more
negative, then …
1. Controller senses an increased exhaust flow
2. Controller gradually closes the general exhaust damper to minimum if required
3. If ΔP set point is still not achieved …
4. Controller gradually opens supply until ΔP set point is achieved
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Direct Pressure Control Sequence of Operations
If fume hood flow decreases and makes space more
positive, then …
1. Controller senses a decreased exhaust flow
2. Controller gradually opens the general exhaust damper to maximum if required
3. If ΔP set point is still not achieved …
4. Controller gradually closes supply until ΔP is achieved
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Direct Pressure Control Sequence of Operations
If the door to the lab opens, then …
1. Controller senses the room ΔP go toward neutral
2. Controller quickly closes supply to minimum if required
3. If ΔP set point is still not achieved …
4. Controller quickly opens the general exhaust damper to maximum if required until ΔP is achieved
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Direct Pressure Control Sequence of Operations
If the lab temperature increases, then …
1. Controller senses temperature increase
2. Controller closes reheat valve
3. If, after 3 minutes, the lab is still too warm …
4. Controller gradually increases supply
5. Controller senses ΔP decrease
6. Controller increases general exhaust to meet ΔP set point
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Direct Pressure Control Sequence of Operations
If the lab temperature decreases, then …
1. Controller senses temperature decrease
2. Controller opens reheat valve
3. If, after 3 minutes, the lab is still too cold …
4. Controller gradually decreases supply
5. Controller senses ΔP increase
6. Controller decreases general exhaust to meet ΔP set point
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Direct Pressure Controller Components8635-C, 8636
8635-C includes:
• 800199 Controller Output Cable, 4-cond., 25 ft.
• 800224 SureFlow Room Pressure Controller
• 800326 SureFlow Room Pressure Sensor w/ Cable
• 800420 24-VAC Transformer with Cable
8636 includes:• 800199 Controller Output
Cable, 4-cond., 25 ft.• 800326 SureFlow Room
Pressure Sensor w/ Cable• 800420 24-VAC
Transformer with Cable• 800775 8636 SureFlow
Room Pressure Controller
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Flow Tracking Control
8681
8650
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Flow Tracking Control
– Measure supply and exhaust air flows– Exhaust flow is more than supply flow (negative lab)
• Difference is referred to as “offset” air– Determine an offset between supply and total exhaust
flows• Total exhaust includes fume hoods, general exhaust,
snorkels, plus other exhaust devices• Offset value is generally listed on the room schedule
– Determined by the number of doors or other penetrations into the lab space
• If unknown, use 10% of maximum exhaust
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Flow Tracking Control
– Modulate supply and exhaust flows to maintain offset
• Once lab is completed, offset value may be adjusted to sufficiently create a negative space
– Measure the supply flow to set minimum ventilation rate and to determine ACPH
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Flow Tracking Control
• Controls flows to numerical set points– Exhaust flow greater than supply flow (labs)– Difference is referred to as offset
• Closed-Loop on Flow– Measure and control supply and exhaust flows
• Open-Loop on Pressure– Differential pressure set point not guaranteed
• Requirements– All flows are measured– Stable air flows
• TSI Models: 8680, 8681 & 8682
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Flow Tracking Control, Calculating Offset Flow
Measured fume hood flows = 1400 cfm
Measured snorkel flows = 150 cfm
Measured general exhaust + = 350 cfm
Total exhaust = 1900 cfm
“Offset” requirement per schedule - = 200 cfm
Supply air flow rate set to = 1700 cfm
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Flow Tracking Control
• The only option for open labs or labs with no suitable reference space
• Labs where containmentis not critical
• Labs designed around competition
• Remember– Doesn’t measure or
guarantee room differential pressure
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Flow Tracking Control
• Engineers/Consultants understand
• ΔP not guaranteed
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Flow Tracking Control Sequence of Operations
If fume hood flow increases and makes space more
negative, then …
1. Controller senses an increased exhaust flow
2. Controller gradually closes the general exhaust damper to minimum if required
3. If offset is still not achieved …
4. Controller gradually opens supply until offset is achieved
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Flow Tracking Control Sequence of Operations
If fume hood flow decreases and makes space more
positive, then …
1. Controller senses a decreased exhaust flow
2. Controller gradually opens the general exhaust damper to maximum if required
3. If offset is still not achieved …
4. Controller gradually closes supply until offset is achieved
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Flow Tracking Control Sequence of Operations
If the door to the lab opens, then …
1. Controller does nothing since it cannot sense the loss of room ΔP
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Flow Tracking Control Sequence of Operations
If the lab temperature increases, then …
1. Controller senses temperature increase
2. Controller closes reheat valve
3. If, after 3 minutes, the lab is still too warm …
4. Controller gradually increases supply
5. Controller gradually increases general exhaust to offset
6. ΔP unknown
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Flow Tracking Control Sequence of Operations
If the lab temperature decreases, then …
1. Controller senses temperature decrease
2. Controller opens reheat valve
3. If, after 3 minutes, the lab is still too cold …
4. Controller gradually decreases supply
5. Controller gradually decreases general exhaust to offset
6. ΔP unknown
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Flow Tracking Controller Components8681-NS, 8682-NS
8681-NS includes:• 800420 24-VAC
Transformer with Cable• 800776 8681 SureFlow
Adaptive Offset Controller
8682-NS includes:• 800420 24-VAC
Transformer with Cable• 1203217 TYPE 1 NEMA
Hinged Box• 800416 DIM COMM cable,
shielded 2-wire, 25 ft.• 800228 8682 SureFlow
Digital Interface Module• 800235 8682 SUREFLOW
DDC CNTL W/O LON
Note: All damper/actuators and flow stations must be added separately. Adaptive offset and flow tracking controllers require the addition of factory start-up.
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Flow Tracking with Pressure Monitoring
• Measure supply and exhaust air flows• Maintain an offset between supply and exhaust
flows • Monitor pressure differential• Differential pressure may vary
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Flow Tracking with Room Pressure Feedback
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Flow Tracking with Room Pressure Feedback
• Flow tracking with room pressure feedback – Formerly referred by TSI as Adaptive Offset Control
(AOC)– Combines Direct Pressure and Flow Tracking controls– Measures supply and exhaust air flows– Measures room pressure differential– Maintains an offset between supply and exhaust flows,
more exhaust than supply– Adjust offset between supply and exhaust flows to
ensure differential pressure set point
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Flow Tracking with Room Pressure Feedback
• Closed loop on Flow– Measures and controls supply and exhaust flows
• Closed loop on Pressure– Measures room differential pressure– Differential pressure measurement is used to
adjust offset to maintain room pressure set point
• Models: 8680, 8681, 8682
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Flow Tracking with Room Pressure Feedback
• Safety of direct pressure with stability of flow tracking
• Requires suitable reference pressure
• Maximum offset limits configurable
• Not used for – Open labs– Labs without suitable
reference space• NOTE:
– Controls on flowfirst
– Pressure is slow reset back to set point
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Flow Tracking with Room Pressure Feedback
• Engineers/Consultants don’t understand
• TSI is unique to this type of control strategy
• Need to sell value of this strategy
• Used to lock-out competition
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Flow Tracking with Room Pressure Feedback Sequence of Operations
If fume hood flow increases and makes space more negative, then …1. Controller senses an increased exhaust flow2. Controller gradually closes the general exhaust
damper to minimum if required3. If offset is still not achieved …4. Controller gradually opens supply until offset is
achieved5. Controller adjusts offset to meet ΔP set point
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Flow Tracking with Room Pressure Feedback Sequence of Operations
If fume hood flow decreases and makes space more positive, then …1. Controller senses a decreased exhaust flow2. Controller gradually opens the general exhaust
damper to maximum if required3. If offset is still not achieved …4. Controller gradually closes supply until offset is
achieved5. Controller adjusts offset to meet ΔP set point
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Flow Tracking with Room Pressure Feedback Sequence of Operations
If the door to the lab opens, then …
1. Controller senses low ΔP
2. Increases offset to meet ΔP set pointa) Controller gradually opens the general exhaust damper
to maximum if required
b) Controller gradually closes supply to minimum if required
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Flow Tracking with Room Pressure Feedback Sequence of Operations
If the lab temperature decreases, then …
1. Controller senses temperature decrease
2. Controller opens reheat valve
3. If, after 3 minutes, the lab is still too cold …
4. Controller gradually decreases supply
5. Controller gradually decreases general exhaust to offset
6. Controller adjusts offset to meet ΔP set point
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Flow Tracking with Room Pressure Feedback Sequence of Operations
If the lab temperature increases, then …
1. Controller senses temperature increase
2. Controller closes reheat valve
3. If, after 3 minutes, the lab is still too warm …
4. Controller gradually increases supply
5. Controller gradually increases general exhaust to offset
6. Controller adjusts offset to meet ΔP set point
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Temperature Control
• To meet comfort demands in a lab environment, integral temperature control is a standard feature on Models 8636, 8681 and 8682 controllers which feature adjustable:1. Temperature dead band range
2. Temperature set point throttling range
3. Temperature set point integral value
4. Reheat valve control direction
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Temperature Control
Temperature Dead Band (TEMP DB, ±0.1° - 1.0°F)
• Defines how sensitive controller needs to be regarding space temperature above and below temp set point
• If the TEMP DB is set to its maximum value (±1.0°F), the controller will not react to changes unless the space temperature rises above or below the set point by 1.0°F.
• If the TEMP DB is set to its minimum value (±0.1°F), the controller will react to space temperature changes 0.1°F above or below set point.
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Temperature Control
If TEMP DB is set to
1.0°F, and the TEMP
SETP is set to 70.0°F,
the controller will not
take corrective action
unless the space
temperature is below
69.0°F or above
71.0°F.
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Temperature Control
Temperature Throttling Range (TEMP TR, ±2.0°-20.0°F)• The temperature range in which the controller fully
opens or closes the reheat valve• Defines reheat valve movement
– Smaller TEMP TR range provides more precise control– Larger TEMP TR range provides more stable control
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Temperature Control
• If TEMP TR is set to ±3.0°F, and the TEMP SETP is set to 70.0°F, the reheat valve will be fully open when the space temperature is 67°F. Similarly, the reheat valve will be fully closed when the space temperature is 73.0°F.
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Temperature Control
Temperature Set Point Integral Value (TEMP Ti VAL)• Manually changes the temperature control PI
integral control loop variable– Increasing TEMP Ti VAL will slow the control system
which will increase stability – Decreasing TEMP Ti VAL will speed up the control system
which may cause system instability
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Temperature Control
Reheat Control Direction (REHEAT DIR)• Determines the temperature control signal’s
output direction– can be set to DIRECT or REVERSE– if the control system closes the reheat valve instead of
opening the valve, this option will reverse the control signal to now open the valve.
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Laboratory Control
• How Does This All Work?– A Model 8636, Model 8681 or Model 8682 controller
receives a temperature input from a temperature sensor (1000 Ω Platinum RTD). The controller maintains temperature control by:
1. Controlling supply and general exhaust for ventilation and cooling
2. Controlling the reheat coil for heating
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Laboratory Control
• The controllers have three configurable supply flow minimum set points. – The ventilation set point (VENT MIN SET) is the minimum flow
volume required to meet ventilation needs of the laboratory (ACPH).
– The temperature supply set point (COOLING FLOW) is the theoretical minimum flow required to meet cooling flow needs of the laboratory.
– The unoccupied set point (UNOCC SETP) is the minimum flow required when the lab is not occupied.
• the supply flow will not be modulated for space cooling when in UNOCC SETP mode; space temperature control will be maintained by modulating the reheat coil.
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Laboratory Control
• The controller continuously compares the temperature set point to the actual space temperature. If set point is being maintained, no changes are made.
• If the space temperature is rising above set point:1. The controller will first modulate the reheat valve
closed.
2. Once the reheat valve has been fully closed for three minutes, the controller will then gradually begin increasing the supply volume by 1 CFM/second up to the COOLING FLOW set point.
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Laboratory Control
• If the space temperature decreases below the set point:1. The controller will first reduce the supply volume.
2. Once the supply volume reaches its minimum (VENT MIN SET), the controller will then start a 3 minute time period.
3. If, after 3 minutes the supply flow is still at the VENT MIN SET flow rate, the controller will begin modulating the reheat coil open to meet the heating demand.
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical EnvironmentsCapabilities Model 8635-M 8635-C 8636 8680 8681 8682
Room pressure monitor x
Room pressure controller x x
Flow tracking controller x x x
Flow tracking controller with room pressure feedback x x x
Low alarm relay x x x x
High alarm relay x x x x
Alarm relay x x
Switch input (occupied/unoccupied) x x x x
Analog output (pressure) x x
Supply flow input 1 1 2 1 1 4
Supply control x x x x x
Exhaust flow input 1 1 1 2
Exhaust control x x x x x
Temperature input (0 - 10V) x x
Temperature input (RTD) x x x
Temperature control x x x
Hood flow input 1 2 7
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
TSI’s Position
• Full-featured controls– Local support– Choice of laboratory control method– Fully digital controls – easy to configure & calibrate– Software specials
• Tailor made to meet specific requirements– Integration into BAS via:
• LON• BacNet (currently via gateway)• Modbus• N2
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Questions?
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Break
Return by 2:45 to Continue
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Demo Lab
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Copyright© 2006 TSI Incorporated
TSI Incorporated – Critical Environments
Wrap Up