Make your own free website on

Downs Rebreather Site

Detailed Prism Photos
General Prism Photos
Detailed Prism Photos
La Paz Research
Other Cool Pics - Page One
Other Cool Pics - Page Two
Related Links
Contact Me











Top view:
Head cap and breathing hoses removed (note the standard 9v battery)
Close-up of electronics with all caps removed:
The top chamber houses the setpoint selector and calibration button for the digital electronics, and the bottom chamber houses the trim pots for the analog secondary. The O2 solenoid is located to the right of the main chamber, and on the outside of the breathing loop.
Bottom view of head:
The sensors are on top, and the depth transducer is under the #2 sensor connector. O2 is injected into the exhaled gas plenum (lower left region) before the CO2 rich gas enters the scrubber through the center bore. Also, a foam pad (not shown) covers the entire assembly except for the center bore when assembled. The chamfered tabs around the perimeter are scrubber alignment guides.
Scrubber (packed w/ 8-12) and bucket:
Secondary Display:

It gives analog readings of each sensor's output, battery charge, and setpoint selection.



Primary display:

LEDs indicate PO2 status and alarm situations

Legend (from left to right):

battery/sensor alarm (bi-color LED lit green to indicate sensor issue), > PO2 .2 below setpoint (blue), >.1 low, PO2 at setpoint (green), >.1 high, >PO2 .2 above setpoint (red)


Red marks the inhale (O2 rich) side, and blue marks the exhale (O2 lean) side







The one on the left is the inhale lung with the ADV. The one on the right is the exhale lung with dump valve and O2 bypass. The devices at the base of each lung are locking drains.





It contains a Schrader valve that is actuated by complete lung collapse.

Photos of SMI Prism closed-circuit rebreather Unit #21. Taken 31/05/2002.

At this time the unit has over 100 hours of diving time on it.

Aftermarket modifications include: conversion to DIR harness system, exchange of Air2 bailout/bcd inflator for long-hose bailout regulator/traditional bcd inflator, grip tape on bucket, black cable protectors, drysuit inflator, etc.