Nitrox and Trimix Blending Station


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Here are some photos and comments on my Nitrox/Trimix blending station.

I started blending Nitrox in Feb 03.

Trimix was added in Jan 04.

      Vance Harlow's
is a "must have" book for the novice gas blender. Look at "Sources for the Home Brewer".

Basic Nitrox Fill Station

It only takes up a 3 x 6 foot corner of the garage.

The components are:

1)Bauer Oceanus Compressor

2)  Air and O2 Blender made from PVC

3)  Homemade Oxygen Analyzers

4)  Oxygen Tank (280 cf "H" tank is pictured, but I use a 330 cf "T" tank now)

5)  Welding Regulator (modified)

6)  Medical Regulator

7)  Manifold, Whips, Gauges, Yokes, clock, thermometer, and humidity gauge

Trimix Filling Station

Looks a lot like the Nitrox station above!

The brown tank supplies He to the Air and O2 blender through an additional hose a couple of inches below the O2 supply. The Atomox He analyzer is connected to the same medical regulator that supplies the downstream O2 analyzer.


- Bauer Oceanus

- 220V/Single Phase (30 amp)

- 4.9 SCFM *

- Synthetic Oil

* Fills an empty AL80 in about 20 minutes.

Since tanks are rarely empty, the average is 4 AL80s per hour.

Air & O2 & He Blender

Oxygen, air, and Helium are mixed in a 2-foot section of 2 inch diameter PVC pipe.

O2 Flow Control

Note: I have replaced this regulator with a Radnor flow meter as seen below, but I am leaving this description in case someone would like to use this option.

This is a Victor welding regulator.

I installed a #77 orifice from a junk medical reg, but this would not give me enough flow. I drilled out the orifice using a #60 drill bit and replaced the original 120 psi gauge with a 30 psi gauge. The 30 psi gauge allows the needle to deflect to just over mid-scale at the flow rate required for 36% FO2.

Helium Flow Control

This is a a Radnor flow meter.

Unlike the Victor regulator above, which reads intermediate pressure, this is a true flow meter.

Nitrox Flow Control and Monitoring

The compressor supplies Nitrox to a manifold which has the following attached:

1) 4 inch pressure gauge

2) Medical regulator

3) Fill whip

4) Moisture Indicator

Medical Regulator: Used to deliver about 2 liters per minute (lpm) of gas mix to the right-hand oxygen analyzer.

Moisture Monitor: Oxyhacker (Vance Harlow) verified with Bauer that temperature alone (regardless of humidity) can be used to adjust filter life. The visual moisture monitor agrees with the Bauer calculations.

Oxygen Analyzers

I made the analyzers from kits (, and mounted both of them in a single box.

The analyzer on the left reads the Fraction of Oxygen (FO2) after the O2 and air are blended. The analyzer on the right reads the FO2 after the mix is compressed.

O2 Whip and Yokes.

I use two yokes:

1) The CGA 870 yoke is used to fill my emergency "D" Tanks

2) The Scuba yoke is used to fill a scuba tank that is also for emergency use.

Basic O2 Transfill Whip (with a few suppliers and prices).

I only use the O2 whip for transfilling my Emergency O2 Tanks.

A Partial Pressure fill whip would need a good "Master" gauge in the proper range

Oil and Condensation Drain

There is a fair amount of pressure released when you drain the condensation from the compressor. This thing vents the air pressure while trapping the oil and water mist.

I spent $5000 on the Fill Station, but I'm still proud of this 0$ contraption!

Cereal Container ("Free" with some cereal)

Scrap PVC (Holes are drilled into the long piece)

Scrubbing pad (a towel also goes inside)

Vent holes

As Long as We're in the Garage

The Gear Side of the Garage


BCs, Fins and Regs

Regulator Workstation

Equipment Drying

Candy found this thing at a clothing store ($40). We use to hang wetsuits and BCs on a fence to drip-dry before bringing the gear inside.

Now, we rinse/soak gear, hang it on this thing, and just roll it into the garage.