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Sonar Adjusting Screw for Apeks 2nd Stage Regulator

Starting at: $32.00


The Sonar Adjusting Screw with Spring Adjuster is an after-market cracking pressure adjustment knob to fit Apeks second stage regulators. A scuba service technician can add this Inhalation Resistance Control Knob to your Apeks 2nd stage regulator so you can control inhalation resistance. The micro Spring Adjuster concealed within the Adjustment Screw enables scuba technicians to make very small adjustments on the main knob.

What the Sonar Adjusting Screw Does

The Sonar Adjusting Screw adds an adjustable cracking/inhalation resistance control knob to Apeks 2nd stage regulators that don't already have it. This could be your Apeks (A/X)T(X) 20 or 40 models.

People who dive deep often like to be able to increase the breathing resistance. This control knob, located beside the RVS switch, adjusts the amount of effort required to start the air flow at the beginning of the inhalation cycle. As it is turned "in" (clockwise), the opening effort will increase. This will make the second stage less sensitive to sudden changes in ambient pressure. Turning the knob "out" (anti-clockwise) will decrease the opening effort to make breathing easier.

This adjustment is particularly useful at deeper depths, or in variable conditions that affect the opening effort of the second stage, such as strong currents or while using a diver propulsion vehicle (DPV). You can use the inhalation control knob to tune your regulator to maintain its peak performance throughout the course of your dive, or you can leave it set in its mid-range position and dive with it as you would any non-adjustable second stage.

Which 2nd Stages Can Be Converted?

These Sonar Adjuster Screw will fit all models of Apeks TX, AT, ATX and XTX 2nd stage regs and work 100% okay.

The main difference between Apeks TX/ATX/XTX 40 and Apeks TX/ATX/XTX 50 second stage regulators is the external adjustment knob that allows you to adjust breathing resistance. By installing the Sonar Adjusting Screw you effectively convert your lower specification Apeks 20 or 40 series 2nd stage regulator into the higher spec 50 series one. Some of the conversions possible include:
Apeks TX40 to TX50,
Apeks AT20 to AXT50, and
Apeks XTX40 to XTX50.

The Sonar Adjusting Screw and Spring Adjuster are made from 316 Stainless Steel and have been CNC machined to a high standard.

Getting the Sonar Adjusting Screw Fitted

Your options to fit this item to your Apeks 2nd stage regulator include:

  1. Have the Scuba Doctor Service and Repairs centre to do it next time you have your regulators serviced and there will be no installation fee.
  2. Get the Scuba Doctor Service and Repairs centre to do right away and pay a $25 installation fee.
  3. Get your local scuba service technician to do it.

(08/15 LRB)

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The Scuba Doctor Australia
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