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Cryonics Institute Ventilation System

by Ben Best

Laying out the ducts

Around the year 2006 CI Director Alan Mole lobbied for the Cryonics Institute to place an oxygen detector in the facility. As time has passed and more cryostats have been installed the level of oxygen in the building has progressively declined. The oxygen levels become particularly low when filling the cryostats with liquid nitrogen and when cooling a patient in the cooling box. Nitrogen gas is not poisonous, but when it displaces oxygen in a confined area it can cause hypoxia or even -- with enough displacement -- be fatal.

In 2008 the oxygen level has been chronicly low even when we are not cooling a patient or filling cryostats. When cooling patients or filling cryostats the oxygen level normally drops below the 19.5% which triggers the alarm on the oxygen detector. (Normal atmospheric oxygen is 20.9%). After much investigation of which system to install -- and at a reasonable price -- we decided upon a Bryant Heat Recovery Ventilator from Air Conditioning Engineers, a local Michigan company.

The Bryant Heat Recovery Ventilator is designed to get good air exchange without significant loss of heat. The means by which this is achieved is by having air leaving the building pass by air entering the building in a cartridge so that air leaving the building can transfer some heat to the air entering the building. For this reason the console has four openings at the top: two for air entering and two for air leaving the building, with both entering and leaving air passing through the cartridge in the console between being outside and inside the building. Stated another way, stale air high in nitrogen and low in oxygen flows through a duct to the console and after passing through the console leaves by another duct to the outside of the building (2 ducts). Fresh air from the outside enters the building through a duct that goes to the console and then exit the console through another duct that blows the fresh air into the building (2 ducts). Thus, the four duct holes in the top of the console allow warm air from the building to warm the cold air from the outside as the two air flows pass each other in the console.

Below are some photos taken during installation of the system, and upon completion of installation.

Placement of the console

Laying out the ducts

Making a hole in the wall

Andy checks-out the hole in the wall

Insulated vents fill the holes in the wall

Tubing to remove condensation goes into another hole in the wall

Tubing goes through ceiling to perfusion room

Tubing dumps condensation in perfusion room sink

Ventilator ductwork

Ventilator Console (note pump at bottom)

Ventilator Condensation Pump

The condensation pump at the bottom of the console pumps the water (which has condensed from the air) through a long tube leading through the ceilings into the basin in the perfusion room. Because the condensate can become stagnant and accumulate bacteria, it is good maintenance to put a cup or two of bleach into the pump about every 3 months. The bleach would be poured in where the black cap is located on the front left side of the condensation pump. The tube removing the condensation emerges from the front right side of the condensation pump.

Good maintenance also means cleaning the filters every 3 months. There are two filters in the console, one of which sits on top of the diagonally-placed cartridge and the other of which sits on the bottom right of the cartridge. Ordinary water should be adequate for cleaning. The cartridge should be removed and cleaned (wiped-off) at least once per year.

Ventilator console with door open showing white cartidge

Filter on bottom-right of cartridge

Valve on output duct

The output duct is completely open when the valve is in the vertical position. We are keeping the valve in the vertical position, although we may close the valve partially on exceptionally cold days to conserve heat.

The ventilator can be set for HIGH (red light), MEDIUM (orange light), INTERMITTENT (green light) or OFF (no light). If the ventilator is HIGH, when we turn on the exhaust fan in the back of the building we can get the oxygen level up to 20.8%. With the exhaust fan on and the ventilator OFF oxygen may get up to 20.7%. But we don't want to run the exhaust fan all the time, which is why we are getting the ventilator. With the exhaust fan off and the ventilator on HIGH, oxygen levels can get to 20.5%. The MEDIUM setting is not much different from HIGH, but may give a reading of 20.4%. INTERMITTENT is MEDIUM ventilation for 20 minutes per hour and OFF for 40 minutes per hour. INTERMITTENT gives oxygen levels of around 20.1%.

Oxygen detector

Ventilator control (H,M,I)