1. Regulators

2. 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.

3. Most Common Regulator
Single Hose
Open Circuit
Demand

4. Single Hose First Stage mounts on the cylinder valve
Second connected by a single hose
Air exhausts from the second stage

5. 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

6. Open vs. closed Circuit Open circuit Rebreathers
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

7. Valve Design Upstream valve Downstream valve Pilot 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.

8. First Stage
Reduces Cylinder Pressure to a working pressure of approximately psi.

9. Piston First Stage Simple design Few moving parts
Piston is exposed to the environment
Sealing kits are available

10. Diaphragm First Stage More complicated design More moving parts
Critical components are sealed from the environment.

11. 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

12. Types of First Stages
Yoke vs DIN

13. Yoke System DIN 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

14. Second Stage
The second stage delivers air at ambient pressure and volume.
Primary second stage
Used by the diver during the dive
Custom Mouthpieces

15. 2nd Stage Features Balanced vs. Unbalanced Adjustable Air flow/Volume
Balanced allows use of a lighter spring
Easier breathing resistance
Adjustable
Adjust breathing resistance
Air flow/Volume
Adjust air flow/volume based on need

16. 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

17. 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

18. 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.

19. LPI Hose
Used to add air directly from the cylinder to the BC

20. HP Console Typically contains May be an SPG only SPG Compass
Depth Gauge
May be an SPG only

21. 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

22. 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

23. Pre Dive check Mouthpiece Hoses Filter Inhalation check
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.