Air Dist for Labs, Hospitals and Clean Rooms-ASHRAE1

Air Distribution for Laboratories, Hospitals and Clean Rooms Dan Int-Hout Chief Engineer / Krueger Richardson Texas

3/22/2011

Today’s Standard Lab?

Purpose Recognize the importance of proper air distribution selection in laboratory designs

Agenda • Defining the Problem – Lab Types – Design Parameters

• Possible Solutions – Types of Air Outlets

• Proving the Case – Case Studies

Defining the Problem

Common Laboratory Types • Biological – contain biologically active materials or involve chemical manipulation • Chemical – organic and inorganic analysis and synthesis • Animal – manipulation, surgical modification and pharmacological observation • Physical – incorporate lasers, optics, nuclear material, high and low temp materials • Isolation – can be infectious or protective in nature

HVAC Design Parameters • • • • • • •

Define Air Change Rate requirements Suppress & Remove Airborne Contaminants Optimize Air Change Effectiveness Control and Direct Room Air Motion Provide Occupant Comfort Room Controls Aid in Fume Hood Containment

Air Change Rates • Air Change Rates per Hour-ACH frequently established by exhaust hood make up air requirement – Typical Labs requires 6 -10 ACH – Animal Housing requires 15 ACH

Example • Room Dims – 10’Wx20’Lx10’H = 2000 ft3 • @ 10ACH = 333 CFM or 1.6 CFM/ft2 ACH = CFM * 60 / Room Volume

Suppress & Remove Airborne Contaminants Factors to Consider: • System Effectiveness • Particulate Concentration & Dilution Rate Measurements: • Particulate Dispersion – Particle Count – Gas Concentration – Contaminant Migration

High Count

Low Count

Optimize Air Change Effectiveness • Efficiency of Dilution • Speed of Extraction • Decrease Age of Air • Improve Operational Efficiency

Environmental Dust Pollen Mold

Copiers Ammonia Benzaldehyde Benzene Isopropanol Combustion Products

Paints Acetates Alcohol Alkanes Benzenes

Computer Butanol Butanole Butoxyethanol Ozone Phosphoric Acid Tolune

Occupants CO2

Floor Coverings Formaldehyde Acetates Styrenes Xylenes

Room air motion is primarily determined by supply air delivery and heat load, not exhaust flows

Control and Direct Room Air Motion Controlled Flow to avoid: • Excessive Drafts • Recirculation • Hot and Cold Spots • Interference with Experiments • Compromise Fume Hood Safety • Temperature Swings Supply air outlets direct air into the space in different ways. Supply outlet type and location must be evaluated to assure satisfactory room air motion.

Laboratory Pressure Controls Energy Efficiency

First Cost

Future Flexibility

Constant Volume

Low

$

Low

2 Position

Med

$$

Low

Direct Pressure

High

$$$

High

Flow Tracking

High

$$

High

 

Flow Tracking with Pressure Feedback

High

$$$

High

 

Safety

 

VAV Systems

Provide Occupant Comfort • Noise – Operating Fume Hoods generate NC levels between an NC 40 to 45 • Temperature – Uniform Temperature – No Stratification • Eliminate Drafts • Ventilation • Humidity

Fume Hood Containment ASHRAE Standard 110: 4.11.2 Supply Air Distribution “Supply air distribution shall be provided to create air jet velocities {distributed towards the hoods}less than half (preferably less than one-third) of the capture or face velocity of the exhaust hoods.” Fume Hood Face Velocity = 100 fpm

Fume Hood Containment Fume Hood Locations • Avoid walkways – Prevent spillage due to walking wake

• Avoid fume hoods near exits – Spills or accidents may increase the danger

Possible Solutions

3 Most Common Types of Air Outlets • High-Induction/Entrainment Outlets • Laminar Flow Outlets • Radial/Forced Displacement

High Induction/Entrainment Diffusers RM

• • • •

Commercial Office Spaces High Velocity Jets Long Throw Designed to Mix in Zone

PLQ-R

1400

Prism

Prism

Animation of High Induction/Entrainment Diffusers

Why Not a High Induction Diffuser in the Laboratory? • High velocity ceiling pattern and colliding jets may enter occupied zone • Results in mixing & re-circulation of air • particles and gases drawn into supply air stream • air ages before it is exhausted

• Operational Efficiency is Sacrificed • Requires higher ACR to reduce particle counts

• Interference w/ Fume Hood • Occupant comfort • Uniform Temperatures Only

Laminar Flow Outlets

• Hospital Operating Suites when used in conjunction with air curtain • Hi-Tech Electronics - Bench Top Applications

Why not a Laminar Flow Device in the Laboratory? • Vertical Column of Air • Velocity 30-100 fpm depending on T

• • • •

Turbulence in space Fume Hood Face Velocity Disturbance No Occupant comfort Operational Efficiency is Sacrificed • Results in higher ACR to reduce particle counts • Non Uniform SpaceTemperature

Animation of High Laminar Flow Diffuser

Radial Forced Displacement Outlets

• • • •

Pharmaceutical & Chemistry Labs University Labs Isolation Wards Animal Holding Rooms

Why a Radial Displacement Diffuser in a Laboratory? • Creates a low velocity radial air flow pattern • Suppresses mixing & re-circulation of air • particles and gases pushed down and away from work area toward exhausts • minimal age of air (one-pass-then-out)

• Operational Efficiency • ACE vs. ACR improved

• Occupant comfort • Uniform Temperatures • Improved Acoustics

• Minimal Fume Hood interference

Animation of Radial Flow Diffuser

Proving the Case

Case Study: Integrated-circuit

crystal growth chamber • Test problem: Determine the efficiency in which particles could be removed from a space based on the type of air distribution device employed.

• Displacement • Parameters: – 41x41x9 Room – 32 ACH – 20°F T

vs. Laminar (Qty=10) - Qty = 10

Case Study: Integrated-circuit

crystal growth chamber

Results: After 4 min. 207% ACE difference

Laminar, 800CFM/Diffuser – low efficiency

Displacement TAD, 600

CFM/Diffuser– High efficiency

TAD-800CFM/diffuser

Case Study: Animal Holding Room

Mock-Up • Test Problem: Determine the rate of decay in an animal holding room

• High Induction vs. • Parameters: – 20x14x9 Room – 15 ACH – 10°F T

Forced Radial Displacement

- (Qty=2)

Case Study: Animal Holding Room Mock-Up-High Induction Diffusers

17:40 min to reach Class 100,000

Case Study: Animal Holding Room MockUp-Forced Displacement Diffusers

13:45 min to reach Class 100,000 29%, ACE improvement

Case Study: Animal Holding Room

Mock-Up • Test Problem: Determine the most efficient room layout and exhaust location in a animal holding room mock up

• High Exhaust vs. Low Exhaust • Parameters: – – – –

Forced Radial Displacement (Qty=2) 20x14x9 Room 15 ACH 10°F T

Case Study: Animal Holding Room

Mock-Up with Ceiling Located Exhaust

Case Study: Animal Holding Room Mock-Up with Low Sidewall Exhaust

•Class 20,000 17%, ACE improvement over ceiling located exhaust

Effective Solutions

Effective Solutions Intrusive Radial flow

Flush Face Radial flow

Performance Matters • Notice Jets – Competition photo published in ASHRAE magazine

• Perforated Metal Physics – Air wants to travel Horizontal or Vertical to the face of the perforated metal – The larger the  T the more difficult it is to throw at a 45° angle

Parallel SCC Unit in a Lab Application Parallel SCC Unit

Lab Pressure Control Valve Critical Environment Outlets

Hospital Air Curtain Systems

Down the road to bad assumptions Total particle counts reductions leads to reductions in infection rates

+ micro-filtered vertical laminar airflow of a specific velocity leads to total particle reductions

= micro-filtered vertical laminar airflow of a specific velocity is the only acceptable air distribution solution

“…what we observe is not nature in itself, but nature exposed to our method of questioning” Werner Heisenberg, physicist

Where Clean Counts • Other than the surgeon’s hands, nothing is more important than sterile in the hospital OR • Through bad choices, we can dirty an otherwise clean environment • Assumptions that hold true in the clean room may not apply in the OR

Fallacy: all vertical laminar is good laminar •

Laminar diffusers do not behave predictably outside a system that does not include these features: 1. Isothermal entry 2. Unbroken arrays 3. Controlled static (HEPA filter?) 4. Proper exhaust location 5. Precise balancing 6. Distributed heat load

OR’s are not clean rooms!

Fact: Vertical laminar can behave badly 

May induce more than expected



Broken arrays may cause chaotic flow



Large arrays produce mass effect





Low velocity may not overpower mass heat source No proof that it works!

A Change of Heart What is needed is a “one pass – then out” system that was sensible, safe, efficient and economical

Enter the air curtain • Air distribution manufacturers realized several things: – Howorth systems did not play well with others – Laminar flow was unpredictable outside of the clean room – Designers needed a scalar design proven to reduce viable particle counts

Enter the air curtain • What an air curtain looks like:

Enter the air curtain • What an air curtain does:

Why air curtains work better 



It doesn’t replace laminar; it helps laminar behave predictably Mechanically friendly

Catching and counting microbes 





Classifications based on viable microbiologic particle counts Counts taken during periods of normal work activity (during surgery) Counts taken a locations where air approaches the site of actual work (incision, instrument tables, etc.)



Reliability to be achieved through repetitive sampling



Minimum sampling 30 cubic feet of air



Record temperature, humidity, ACH, delta P



Class 1 Microbiologic Cleanliness: 1 particle per cubic foot

Catching and counting microbes 

Real time tests –

13 tests

–

2 hospitals

–

8 surgeries

–

5 surgeries were total knee replacements

–

Meets all requirements of definition

–

Class 1 Microbiologic Cleanliness inside the curtain, Class 5 outside

There is only one air curtain systems on the market based on designs tested during actual surgery

What should you do? 



Ask facility what level of microbiologic clean air they want Use laminar arrays when they count – –



Don’t apply blindly without recognizing the limitations Keep the big picture in mind

Use air curtain systems when they count – – – –

Large OR’s or high ACH Invasive or critical surgery Other mechanical equipment placement important Don’t apply blindly without recognizing limitations

“sensible, safe, efficient and economical design” Harold Laufman CORE Chairman 1972-1979

Summary • The path to clean OR air has not always been clear • Early pioneering efforts did not provide complete solutions • Assumptions not based on microbe counts have proven wrong • There is such a thing as a harmful approach • There are solutions based on counting microbes • Air distribution must be part of a complete approach • As surgery advances, we must advance with it • Not all manufacturers may be qualified

Cleanroom Product Overview

Cleanroom Overview Market Characteristics - Size: $200M Worldwide – NA $50M - A few companies competing for the larger jobs - Focus on traditional HEPA/ULPA products

Trends - Regulations: ISO, SEMI, IEST, UL, CE, FM - NanoTechnology will be the next driver in the US market. - New greenfield projects are down in US. Retrofit projects are more common.

North America Cleanroom Market Fan Filter Unit = $20 M

Other = $5 M

10% 40%

MiniEnv. = $5 M

10%

40%

Terminal Filter = $20 M

Technology Overview

HEPA Filters: How They Work Dirty Air

Pre-Filter

Straining

HEPA Filter

Clean Air

Impingement

Interception

Diffusion

Brownian Effect

Laminar Flow in Cleanrooms What is Laminar Flow? • Laminar Flow is usually HEPA filtered. Laminar flow removes particles and creates a clean zone. It does this by maintaining a minimum velocity.

Central Air System SUPPLY AIR AIR DUCTS TO EACH FILTER

RETURN AIR AHU TERMINAL FILTER RETURN AIR

CEILING GRID HEPA/ULPA FILTER CLEANROOM CLASSIFICATIONS ENGLISH SI 1 M1.5 10 M2.5 100 M3.5 1000 M4.5 M5.5 10,000

LAMINAR AIR FLOW

HOLLOW RETURN WALL PERFORATED RAISED FLOOR

Pressurized Plenum AHU

SUPPLY AIR

POSITIVE PRESSURE PLENUM (RELATIVE TO ROOM)

HEPA/ULPA PANEL FILTER RETURN AIR

CEILING GRID WALL CLEANROOM CLASSIFICATIONS ENGLISH SI 1 M1.5 10 M2.5 100 M3.5 1000 M4.5 10,000 M5.5

LAMINAR AIR FLOW PERFORATED RAISED FLOOR

Fan Filter Unit System SUPPLY AIR

NEGATIVE PRESSURE PLENUM (RELATIVE TO ROOM)

AHU

FAN FILTER UNIT (MAC 10) RETURN AIR

HEPA/ULPA FILTER CLEANROOM CLASSIFICATIONS ENGLISH SI 1 M1.5 10 M2.5 100 M3.5 1000 M4.5 10,000 M5.5

LAMINAR AIR FLOW

HOLLOW RETURN WALL PERFORATED RAISED FLOOR

Fan Filter Units Standard Features • Low sound, low watts, low profile • Solid State or Digital Speed Control • Snap-in prefilter; no tools required • Walkable plenum • UL Listed and CE marked • Various sizes and voltages available • Exceeds latest ISO 14644

Options • Room-Side Replaceable (ARS) • ULPA Filter • Airflow Indicator Light • A/C Collar (10 & 12 in dia.) • Painted or Stainless Steel Exterior • Power Cord • Challenge and Test Port • Knife Edge • Custom-Sizes Available

Data Comparison

PSC motor ECM motor

Unit Motor Average Watts @ DBA Size HP Airflow 90 FPM Sound 24x24 1/5 325 150 48 24x48 24x24

1/5 1/3

650 325

190 80

50 46

24x48

1/3

650

105

48

FFU System Summary • Fan Filter units offer the most cost effective method of supplying Clean Room Air quantities, with the lowest maintenance and energy costs. • These include moth PSC and ECM constant flow rate motor driven units. • Available Smart Control Systems provide both setpoint control and monitoring of system performance • Cost savings from optimized performance and reduced down-time offset the investment in upgraded control systems.

Specialty Air System Summary • Hospitals can provide a safer Operating Room environment with air curtain air delivery systems than with “laminar” systems. • Laboratories with Fume Hoods require special air delivery systems to ensure that supply air doesn’t cause outflow from the hood opening. • Fan Filter units offer the most cost effective method of supplying Clean Room Air quantities, with the lowest maintenance and energy costs.