PAPR (Powered Air-Purifying Respirator)

DIY PAPR for health workers wiki.

Update on 21st May.

• Uploaded source files, finalizing design and test.

Update on 16th April.

• Battery test using a 20,000 mAh power bank -- 9 hours 4 minutes.

Update on 15th April.

• Now using a 20,000 mAh power bank that is smaller, cheaper and easier to get.
• Testing enclosure using 6mm Acrylic + 3D print fan blower adapter.

Update on 13th April.

• Tested a 12.8V 7.5Ah lithum battery, the fan worked for 15 hours, with less than 25% volume left.
• Tested an all 3D print enclosure, the cost was ~300 AUD. Changed to 3D print + laser cutting scheme.

Update on 11th April.

• Tested PC fan (1200 RPM), the static pressure was not sufficient. Probably a high speed fan is required.
• Changed design to blower fan which has higher static pressure.

Specifications (ref)

• Battery life: > 8 hours (preferred 10 hours or longer)
• Capacity per Minute (Metric): 150 to 230 litres per min (2.5 - 3.8 L/sec or 5.3 - 8.12 CFM)
• Resistance to flow (N95 filter):
  • 0.56 cmH₂O @1L/sec, 0.74 cmH₂O @5L/sec, <1.50 cmH₂O @ 14L/sec.
  • or 55 Pa @1L/sec, 73 Pa @5L/sec, < 147 Pa @14 L/sec.

Materials

• Blower fan
  • Air volume: 0.74 m²/min (26.13 CFM).
  • Static pressure: 1.0 inchH₂O (2.54 cmH₂O or 248.84 Pa).
  • Power consumption: 12 V x 0.86 A = 10.32 Watts (12.4 V x 0.38 A = 4.712 Watts as measured).
  • 3D-printed adapter [in progress].
• Power bank
  • Capacity: 20000 mAh.
  • Voltage regulator: USB 12V step-up power cable.
  • Slide switch.
• CPAP/BiCAP bacteria filter
  • In-flow diameters: 22 mm inner, 26 mm outer.
  • Out-flow diameters: 19 mm inner, 22 mm outer.
  • 3D-printed filter adapter [in progress].
• Laser cutted pannels for enclosure
  • 6 mm Acrylic.
  • M3 screws x 10.
  • Silicone glue.
  • Silicone tape.