Negative Pressure HEPA Filtration Unit for Isolation Rooms and Other High Risk Areas: Introduction, Parts of Instrument/Unit, Working Mechanisms, Applications and Keynotes

Introduction

“Negative Pressure HEPA Filtration Unit” is useful for hospital (isolation ward that keeps patients with infectious illnesses or immunocompromised individuals who are susceptible to infections from others, away from other patients, visitors, and healthcare workers) and molecular laboratory (Sample Aliquoting and RNA Extraction Room to minimize cross contamination and infection to laboratory personnel). Negative air pressure is the by which the air pressure is lower in one site in comparison to another. Regarding negative room air pressure, the air pressure inside a given room is lower than the pressure outside the room, generating air to flow into the room from the outside.

The certified HEPA air filter is highly effective in removing microbes-sized particulate and it demonstrates efficiency on 0.3-micron particles. 0.3-micron particles are representative of most difficult particle size to capture, even more difficult than particles smaller in size. This installation unit will work roughly representative of minimum efficiency for virus, bacteria and other airborne particulate removal.

Parts of Instrument/Unit

The main parts of unit has cabinet, base and motor.

Cabinet: It is made of heavy gauge steel, welded cabinet with chemical resistant powder coat finish.

Base: It is standard base includes four swivel casters.

Motor: It is dynamically balanced, precision external rotor motor to insure quiet, energy efficient and reliable operation.

Specifications of XJ2 Negative Pressure Hospital Grade HEPA Filter System

Air Flow Capability	Infinitely adjustable from 115 CFM to 1000 CFM
Sound Levels	35 dBA @ 115 CFM, 66 dBA @ 775 CFM at 4 feet from the unit
Power requirements	120 Vac, 60 Hz, 4 Amps, 400 Watts OR • 230 Vac, 50 Hz, 2 Amps, 400 Watts
Prefilter	(80-85% ASHRAE efficient)
Primary Filter	• HEPA (≥ 99.97 DOP efficient on 0.3 microns) • HEPA filter is oversized with 131 sq. ft. of media • Oversized HEPA allows for minimum pressure drop • Oversized HEPA allows for maximum filter life and minimum handling  • Each HEPA filter individually tested and certified
Standard Accessories Included with every XJ-2	• Individually tested HEPA • Window Adapter Kit to exhaust filtered air • 6” diameter flex hose  • Dirty Filter Gage  • Variable speed control • Portable Base • Prewired with electrical cord and molded plug
Optional Accessories	• Security Cover • Wall Mounting Kit • Recirculation Plenum

Working Mechanism

The working mechanism of ‘Negative Pressure HEPA Filtration Unit’ completes into following steps-

Interception: Particle comes within one particle radius of a filter fiber and then the articles remain trapped or “filtered” by the filter media due to Van der Waals forces. Larger particles are easier to capture by Interception.

Inertial Impaction or Impingement: Heavier particles collide with filter fibers due to their inertia as air makes its way through the torturous path around the filter fibers. Larger particles are easier to filter by inertial impaction.

Diffusion: Particles increase in random motion because of to Brownian motion as particle size decreases. Greater random motion increases probability of particle to make contact with filter fiber and smaller particles are actually easier to capture due to diffusion mechanism.

Straining or Sieving: It is simple and the last phase of working of ‘Negative Pressure HEPA Filtration Unit’.

Applications

• Nowadays Negative Pressure HEPA Filtration Unit’ is the most commonly applied in hospital and clinical diagnostic as well as molecular laboratory for minimizing cross-contamination and infections.
• It is commonly used in hospital to isolate patients with contagious, airborne diseases such as , tuberculosis, measles, SARS, MERS, and COVID-19.
• Negative pressure application is mandatory in extraction room of COVID-19 PCR laboratory.

Keynotes

• HEPA stands for high-efficiency particulate air.
• Features of XJ2 instrument/system/unit are quiet , affordable, portable, compact, fast and flexible installation.
• Installation cost of XJ2 negative pressure hospital grade HEPA Filter System for isolation room is nearly $5,995.
• There are four types of isolation rooms and they are class S, class P, class N and class N among them two are only negative pressure rooms (class N and class Q).
• Class S isolation room: It is a neutral or standard air pressure room having normal air conditioning and it applied for contact isolation.
• Class P isolation room: It is a positive pressure rooms and it used for immunocompromised patients saving from potentially dangerous particles/microbes from other patients, visitors, or healthcare workers.
• Class N isolation room: It is a negative pressure room in which people outside of the room are protected from any infectious airborne particles inside the room. It is equipped with an exhaust system that removes more air than the room is being supplied with where anterooms are not always necessary.
• Class Q isolation room: It is a specialized type of negative pressure room that include additional infection control measures such as an anteroom and are used in situations requiring quarantine. This type of room has alarms to alert staff to loss of pressure within the room, self-closing doors, a separate bathroom for the patient, and a ventilation system that does not allow any exhausted air to return into the room. HEPA filter is also another requirement of this type of room.

 

Monitoring to Validate Negative Pressure

Negative pressure is monitored and validated by following ways-

1. Periodic or continuous testing is acceptable
2. Chemical aerosols or smoke tubes
3. Differential pressure sensing devices
4. Physical indicators or flutter strips

Frequency of Negative Pressure Monitoring

Frequency of negative pressure monitoring is mandatory in following situations-

1. Always check before patient occupancy.
2. When occupied by a patient, check daily.
3. When not in use, or in use by patients not suspected to be infectious, rooms should be checked monthly.

Efficiency of Negative Pressure Filtration Equipment

CDC guidelines call for HEPA efficiency- HEPA efficiency to be ≥ 99.97% on 0.3-micron particles per military standard 282

What are the CDC Guidelines for Isolation Rooms?

The CDC Guidelines for Isolation Rooms are as follows-

1.  The air filtration flow rates must be to attain 12 air changes per hour (ACH)
2. Negative Pressure should be greater than .01 inches w.g.
3.  Monitoring to validate negative pressure is mandatory.
4. The air filtration efficiency should to be 99.97% or higher as measured against 0.3-micron particle size(HEPA).
5.  All air from the isolation room shall be exhausted directly to the outdoors, except for isolation rooms that are reconstructed from standard patient room from which it is impractical to exhaust directly outdoors may be provided with recirculated air from the rooms exhaust on the condition that the air must first pass through a HEPA filter.

 

Further Readings

1. https://cdn.shopify.com/s/files/1/0104/6462/4698/files/XJ_2.pdf
2. https://cdn.shopify.com/s/files/1/0104/6462/4698/files/XJ-2-Presentation.pdf
3. https://cdn.shopify.com/s/files/1/0104/6462/4698/files/XJ2-Owners-Manual.pdf
4. https://www.cdc.gov/infectioncontrol/guidelines/environmental/background/air.html
5. https://purennatural.com/products/xj2-negative-pressure-hospital-grade-hepa-filter-system-for-isolation-rooms
6. http://healthfacilityguidelines.com/ViewPDF/ViewIndexPDF/iHFG_part_d_isolation_rooms
7. Reference ASHRAE 170-2017
8. https://www.uofmhealth.org/health-library/abo4381