Saiver HEPA Filter Units (HFU)

HEPA filter unit

Mobile Modular HEPA Filter Units from Saiver converts any general ward into a negative pressure isolation room. This is an important application of HEPA filters to protect healthcare professionals and patients alike in hospitals against airborne viruses and pollutants that can compromise safety.

The HFU air purification system has 2 main functions:

  1. Convert an existing general ward into a negative pressure isolation room.
  2. Function as a recirculating HEPA air cleaner, important in high-risk areas such as ER waiting rooms and treatment areas.

The HFU is equipped with 50mm G4 pre-filters and pharmaceutical-grade HEPA H13/14 filters. H13 filters are tested and certified to capture at least 99.97% of microscopic particles 0.3 microns in size. They capture particles smaller or larger than 0.3 microns at higher efficiencies.

Converting an existing ward into a Negative Pressure Isolation Room

Healthcare facilities with negative pressure isolation rooms are ideal for caring for patients with COVID19. Unfortunately negative pressure isolation rooms are not common in Philippine hospitals. 

To convert an existing ward into a negative pressure isolation room, existing air exhausts are sealed, and HFUs are ducted through a window or wall opening.

The commonly accepted pressure difference for negative pressure isolation room ranges from -5 Pa to -20 Pa, depending on the country's standard.


Coronaviruses have diameters between 0.065 and 0.125 microns. When the virus travels in the air, they typically do not travel by itself. Viruses are expelled through droplets of saliva that are usually 5-10 microns in size.

While HEPA filters cannot eliminate all risks against COVID19, it helps reduce risks from airborne infection by filtering the air.

HFU Standard Features

Saiver HEPA filter units are designed for heavy duty use in the hospital setting. They are constructed with commercial grade materials. Standard features follow:

  • Easy to deploy in the hospital setting - narrow upright design with 6 smooth rollonig wheels with foot brakes
  • High efficiency airflow - EC fan with high efficiency IE4 motor rated for 60,000 hours of maintenance-free operation
  • Zero-bypass HEPA filter frame - Contaminated air could not bypass the HEPA filter
  • Double-skin cabinet - extruded aluminum profile, EUROVENT certifide mechanical performance for ensuring contaminated air cannot escape the unit once inside
  • Hinged Door for rapid filter replacement - quick access to both the HEPA filter and 50mm pre-filter for replacement or maintenance


Model CADR / Airflow HPEA filter in mm Rated Power Rated Current Noise at 1m Length Width Height Discharge module
  l/s (m3/hr) Height Width Length kW A dB(A) mm mm mm Add mm
HFU-3 300 (1080) 610 305 290 0.3 1.8 53 644 550 1300 410
HFU-5 500 (1800) 610 610 290 0.5 2.2 56 644 704 1300 410
HFU-7 700 (2520) 610 610 290 0.6 2.6 58 685 704 1300 410

Optional Features

The HFU can be augmented with accessories such as carbon prefilters, ionizers, UV lamp, air quality sensors, photocatalytic oxidation, air airflow control. We configure the HEPA Filter Units according to the specific requirements of the healthcare facility.

HFU Sizing

Air changes per hour (ACH) is the number of times the air in a given room is changed within an hour. The required ACH depends on the use of the room. Based on AHAM guidelines, recommended ACH follows:

Air Changes per Hour
Contamination Level Application ACH
Residential Residential, Offices with few visitors 4
Light Offices/Clinics/Consultation room with multiple visitors 6
Moderate / Commercial Lobbies 8
Heavy / Industrial Very crowded Areas/Industrial pollution 10
Critical Medical isolation 12
Immuno-Compromised Medical Isolation with Immuni-Compromised Patients 15


To dermine the required Air Flow, we multiply the volume of the room with the ACH and convert to liters per second or cubic meter per hour.


Room size: 10m (length) x 7m (Width) x 2.1m (Height) = 147 cubic meters

Air change: 12 air changes/hour (medical isolation)

Air flow needed = 147 meters x 12 air changes per hour = 1764 cubic meter per hour of air change

Or in liters per second: 147 x 12 / 3600 = 0.49 cubic meter per second = 490 liters per second.

For this scenario, we recommend the HFU-5 model.