Regulators

Objectives• Describe the regulator most commonly used for recreational scuba.• Compare a single hose regulator to a double hose regulator.• Compare an open circuit system to a closed or Semi-Closed system.• Contrast upstream valves with downstream valves.• Describe the operation of a pilot valve regulator.• Identify and describe the function of the:

– First Stage– Primary Second Stage– Octopus/Extra Second Stage (ESS)– LPI hose– Console

• Explain why it might seem harder to breath while laying on your back.• Give 4 reasons why the regulator might breathe “wet”. • Explain why a regulator might free flow.• List considerations for a pre-dive check of your regulator including the

significance of a discolored 1st stage filter.• Describe proper care and maintenance of your regulator.

Most Common Regulator

• Single Hose

• Open Circuit

• Demand

Single Hose

• First Stage mounts on the cylinder valve

• Second connected by a single hose

• Air exhausts from the second stage

Double Hose

• Both stages in a single housing mounted on the cylinder valve

• Mouthpiece is just a mouthpiece

• Air exhausts from the housing behind the diver

Open vs. closed Circuit

• Open circuit– Gas exhausts into the water

• Rebreathers– Semi closed Circuit

• Small volume of gas periodically escapes

– Closed Circuit• No gas escapes

– Typically used by technical divers• Require more

– Training– Equipment– Preparation

Valve Design

• Upstream valve– Forced closed by air pressure– Failure can shut off the flow of air.

• Downstream valve– Air pressure acts to open the valve– Failure typically results in free flow

• Pilot valve– Uses air pressure to both open and close the

valve.

First Stage

• Reduces Cylinder Pressure to a working pressure of approximately 125-140 psi.

Piston First Stage

• Simple design

• Few moving parts

• Piston is exposed to the environment– Sealing kits are available

Diaphragm First Stage

• More complicated design

• More moving parts

• Critical components are sealed from the environment.

Balanced vs. Unbalanced• Unbalanced First stage

– Intermediate pressure will drop with cylinder pressure

– Breathing resistance increases

• Balanced First stage– Intermediate Pressure remains stable

throughout change in cylinder pressure– Breathing resistance remains the same

• Can be either Piston or Diaphragm

Types of First StagesYoke vs DIN

• Yoke System– Typically used for lower pressure systems– May be easier to use– More common in USA

• DIN System– Typically used in High pressure systems– O ring is contained/more secure– May not be as convenient in the USA

Second Stage

• The second stage delivers air at ambient pressure and volume.– Primary second stage

• Used by the diver during the dive• Custom Mouthpieces

2nd Stage Features

• Balanced vs. Unbalanced– Balanced allows use of a lighter spring – Easier breathing resistance

• Adjustable– Adjust breathing resistance

• Air flow/Volume– Adjust air flow/volume based on need

Trouble Shooting

• Regulator breathes hard when supine– Pressure difference between 1st and 2nd stage

• Regulator Leaks water– Torn mouthpiece– Torn Diaphragm– Inverted position– Exhaust valve problem

Trouble Shooting cont.

• Regulator Freeflows– Second stage lowered purge down– Sand in purge– Sand behind lever “ears”– Low pressure seat problem

• Immediate

– Intermediate Pressure problem• Intermittent

Octopus/Extra Second Stage

– Octopus/Extra Second Stage• Used in the event another diver runs out of air• offers slightly more breathing resistance than the

primary. – reduces the likelihood of a free flow while diving.

• LPI Hose– Used to add air directly from the cylinder to

the BC

• HP Console– Typically contains

• SPG• Compass• Depth Gauge

– May be an SPG only

Care and Maintenance

• Keep the interior of the first stage dry– Have the dust cap in place when the regulator is off

the cylinder valve

• Fresh water rinse after diving– Ideally rinse with flowing water while on the cylinder– Soak with the dust cap in place.– Make sure to rinse the quick release mechanism on

the LPI

• Annual service

Purchase/Performance Considerations

• Can the regulator meet demand at depth or high levels of exertion?

• Can the regulator deliver high flow rates at low cylinder pressure?

• Breathing adjustment• Flow/volume control• Exhaust resistance• Budget• Durability

Pre Dive check

• Mouthpiece– Check for tears or holes

• Hoses– Check for cracks, holes, soft spots, bubbles– Slide the stress relievers away from the 1st stage

• Filter– Check for discoloration

• Green = salt water in regulator• Rust = rust in tank• Oil = oil from the compressor• Black dust = carbon from the compressor filter

• Inhalation check– Should not be able to inhale easily with your thumb over the filter

opening in the 1st stage.