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Gas Generators – Part 3 – Zero Air Generators

26 Sep 2023

My next installment will cover Zero Air Generators.  There are several models Restek sells, which vary by output flow rates and purity.  Each of these models will be discussed below.  They will include Parker 75-83NA, HPZA-3500, HPZA-7000, HPZA-18000, HPZA-30000.   The most noticeable difference between these models is capacity.

75-83NA Zero Air Generator

75-83NA

The Restek part number for this generator is 20684.  This model is capable of 1000cc/min.  The preferred installation is for this unit to be wall mounted, although it can be installed onto a benchtop.  The Parker Installation, Operation and Maintenance manual can be found here  TI-7583H.pdf (parker.com)   The 75-83NA model takes compressed air and purifies it into zero grade air using a combination of filters and a catalyst. The prefilter removes oil mist, particulates, and moisture from the incoming compressed air supply.  The catalyst oxidizes any remaining hydrocarbons from the compressed air supply into carbon dioxide and water.  A second, final filter, removes additional particulates.

Maintenance requirements for these generators include an annual maintenance kit, Restek 21646 (Parker MK7583) and a catalyst tower, Restek 22005 (Parker 75394, which needs to be replaced every two years).

Included in maintenance kit 21646 is:

  1. Prefilter (Parker 050-05-BX)
  2. Final filter (Parker A01-0185)

A couple of specifications to keep in mind; for every generator model listed in this post, the minimum/maximum incoming (compressed) air temperature is 60°F/100°F and the minimum/maximum incoming (compressed) air pressure is 40psi/125psi.

HPZA-3500

The Restek part number is 20680.  This model has a maximum flow rate of 3500cc/min.  This unit is larger/heavier than the 75-83NA model, so the preferred installation is bench top, but it can be mounted on the wall.  The Parker Installation, Operation and Maintenance manual can be found here TI-HPZA-3500H.pdf (parker.com)

In this model, compressed air is forced through two prefilters, followed by a catalyst tower, and finally through a final filter.  The annual maintenance kit, Restek 21647 (Parker MK7840), includes the following:

  1. First stage prefilter (Parker 100-12-DX)
  2. Second stage prefilter (Parker 100-12-BX)
  3. Final filter (Parker GS-050-05-95)

A catalyst tower, Restek 22004 (Parker 76810), is also available.  Unlike the replacement schedule for the 75-83NA model, the catalyst tower should be replaced when the following occurs (according to page 7 of the manual):

The catalyst module in the Parker Balston Zero Air Generator should be changed when the “Check System” LED is illuminated or blinking to maintain the hydrocarbon removal specification for the unit.

Catalyst module for Parker Balston Zero Air Generator

HPZA-7000

The Restek part number for Parker model HPZA-7000 is 20681.  As you may have guessed, the maximum flow rate is 7000cc/min.  The manual is the same as for HPZA-3500 TI-HPZA-3500H.pdf (parker.com), and so is the maintenance kit (Restek 21647, Parker MK7840), but the catalyst tower is different (Restek 22006, Parker 76820).  Preferred installation is on a bench top.  

HPZA-18000

The Restek part number for this generator is 20682.  The maximum flow rate is 18000cc/min.  Once again, the maintenance kit is the same (Restek 21647, Parker MK7840) but the catalyst tower is different 22007 (Parker 76811).

HPZA-30000

The highest capacity zero air generator Restek sells is Parker’s HPZA-30000 model, Restek 20683.  This unit has a maximum flow rate of 30000cc/min.  As you may expect, the maintenance kit is the same (Restek 21647, Parker MK7840) but the catalyst tower is different 22008 (Parker 76821).

As you can see, generator selection is straight-forward; simply select the zero-air generator which matches your flow needs.  Then, instead of the drudgery of changing zero-grade air cylinders, use a zero-air gas generator instead.   Thanks for reading.