Oxygen Addition
Oxygen addition on the KISS rebreathers is what we call a buffered manual control system. The oxygen is added in two ways. Via the manual add valve, continuous flow and manually.

By continuous flow: The manual add valve holds the 0.0035 orifice. Once the oxygen valve on the cylinder has been turned on, there will be a constant flow of oxygen into the rebreather at all times. The flow rate is adjustable and can be set as high as 1 liter per minute. But most divers will want to keep it around 0.5 to 0.7 liters per minute.

The flow rate is just enough to keep the diver from becoming too busy underwater. What does this mean for the diver? When he reaches his desired operating depth, the PPO2 is manually adjusted and brought to the appropriate level. As long as the diver isn’t working hard or moving up and down in the water column, oxygen will be added infrequently.

How does a diver determine where the flow rate should be set? The simplest way is to go diving. Are you constantly adding gas, even while at depth, when you aren’t working hard or moving up and down? If this is the case, then the flow rate should be increased. Are you finding that the PPO2 is slowly increasing during normal diving activities? If yes, then more oxygen than the diver can metabolize is flowing into the loop. The flow rate should be reduced.

Manually: Oxygen can be added to the loop manually by pushing the manual add valve button. In general, when the valve button is not depressed, the oxygen is forced through the 0.0035 orifice at a steady rate. When the button is depressed, it is like a door has been opened and a larger amount of gas is allowed through the valve. The diver will push the button more at shallow depths and less at deeper depths.
Jetsam PPO2 Displays
The Jetsam displays have three independent, backlit PPO2 displays. Each display has its own housing, battery and sensor, making the system completely redundant. The batteries are user changeable. Each display can be replaced independently and spares are easily affordable.
Scrubber Canister
The Classic KISS scrubber canister has an axial flow design. It is a durable, easy to fill canister which holds approximately 6 pounds of absorbent. Sofnolime 797 grade of absorbent was used for testing. The gas flows down the center of the scrubber tube and then comes up through the scrubber material where the carbon dioxide is scrubbed out.

The canister is accessed by removing the “hat” from the scrubber head. Then using the special KISS tool the large bronze draw nut is removed. The canister is now loose and can be removed from the scrubber head.
Bailout Mouthpiece
The Classic KISS Dive Surface Valve (DSV) has a built-in bailout 2nd stage regulator; this means that the diver can go from closed circuit to open circuit with a twist of a knob. The knob on the DSV is used to either open the rebreathers breathing loop or when closed, allow the diver to breath in open circuit mode.

The DSV can provide the diver with an alternate method of adding diluent gas or even an alternative diluent depending on the connection. It is a simple way to purge the rebreather for verifying the sensor readings. Also, it can prevent panic in the case of a malfunction in the rebreather by allowing a fast, simple way of getting your next breath.

NOTE: * The diluent bottle is not adequate bailout. When diving a rebreather, a separate bailout bottle should always be carried.
Counterlungs
The Classic KISS uses 2 individual back mounted counterlungs, and are attached to the scrubber head from the inside of the counterlung case. Back mounted lungs leave the diver’s chest area clear and reduce the number of hoses and fittings compared to the over the shoulder counterlungs found on other rebreathers. The lungs are MSR heavy duty dromedary bags. They are inexpensive to replace and readily available worldwide. The Classic comes standard with a 2 liter and a 4 liter counterlung. Smaller and larger sizes are available upon request.

With the Classic KISS rebreather, it is important that the counterlung volume match the diver’s tidal volume. This will give the diver exceptional buoyancy control and eliminate the risk of overfilling the lungs. It is also important that the rebreather sit tight and as high up on the diver’s back as possible for the best work of breathing (WOB). A high WOB can be caused by an ill-fitting harness which allows the unit to float away from the diver’s body.
Automatic Diluent Valve
The automatic diluent valve (ADV) on the Classic KISS is used to draw the diluent gas into the breathing loop. A diluent gas is necessary as the loop must be filled with a breathable gas mixture. As we drop in the water column, the gas in the loop compresses and the volume left will not be enough to breathe. The volume of the loop will also be decreased as you metabolize the oxygen

When the volume of gas in the loop has decreased, the diver simply inhales hard to trigger the ADV. The operation is similar to a 2nd stage regulator. Suddenly finding yourself unable to get a breath during a rapid descent could be a panic inducing situation. The ADV will help eliminate that as no hands are required to trigger it.

The diluent gas can be air, nitrox or trimix. Generally air or trimix are normally used and the nitrox is reserved for shallow applications, such as pool demos or shallow reef diving.

Diluent can be added several different ways:

ADV: Using the ADV to add diluent gas to the loop is simple and convenient as it has a hands-free operation. This valve is triggered when the gas in the loop has either compressed or the loop has been breathed down.

DSV: Diluent can also be added two other ways using the DSV. First, the diver can close the breathing loop completely and go to open circuit mode. The diver takes a breath off open circuit and then opens the DSV and exhales the gas into the loop.

Lastly, diluent can be added by turning the knob on the DSV towards the closed position only a quarter inch, for a couple of seconds. This will cause the second stage to trigger and gas will blow directly into the loop.
Cylinders and Attachment Methods
A variety of cylinder sizes can be used with the Classic KISS; with 13 cuft cylinders having the most advantages. As the limiting factor on a rebreather is the scrubber duration, this provides plenty of gas. A 13 cuft oxygen cylinder will provide 5 hours of oxygen at a consumption rate of 1 liter per minute. A 13 cuft diluent cylinder will provide enough gas for an experienced rebreather diver to do two, 1 hour long dives to 150 ft.

Jetsam highly recommends that you carry more gas than just the diluent. It should be in the form of emergency bailout, open circuit gas in a separate cylinder. A larger diluent cylinder is not an adequate bailout gas supply.

Other advantages to using 13 cuft cylinders are the size and weight. They fit the Classic KISS well and have good balance. They are easy to travel with to a local dive spot and also pack easily in a suitcase for an over seas trip.

The Classic KISS uses a hose clamp system for cylinder mounting. The mounting brackets do have large slots so any other mounting system on the market can also be used.