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Third Lung Frequently Asked Questions

General What is the advantage of Direct Drive surface supplied air unit?
  The Third Lung 275, 325 and the 460 look a lot alike. What are the differences?
  Hooka diving looks like snorkeling. Do I need to be trained?
  What about diving wrecks or in kelp?
  Is it hard to pull a Third Lung along the surface while diving?
  Will a Third Lung flip over?
  What happens if the engine stops?
  How long are the hoses?
  Why do you use a common 60-foot hose and then give each diver a 20-foot hose? Why not give each diver an 80-foot hose instead?
  Why do you say that divers can descend "from 45 to 75 feet"? Why the range?
  Those little SCUBA bottles used in the egress system seem expensive. Why can't I just use a surface reserve tank attached to the Third Lung?
  Why don't I see more Third Lungs around?
Operation Why doesn't the Third Lung have an intake filter?
  How do you keep the exhaust fumes out of the engine?
  How much maintenance is required on a Third Lung?
  I've heard that only a few compressors are designed for diving and that most are for construction purposes. Is your compressor designed for construction or diving?
  Why do you use plastic swivel fittings instead of metal fittings? Won't these break?
  Can the cases on your 275-DD and the 325-DD Third Lungs stand up to the temperatures, UV exposure, and possible rough treatment that one might expect on a boat?
  I'm concerned about room on my boat. How much space and weight does a Third Lung take up when stored?
Frequently Asked Questions | General Questions
 

What is the advantage of Direct Drive surface supplied air unit?


In compressor design, simple is better. The Third Lung Direct Drive units don't have belts and pulleys. Fewer components mean even fewer maintenance concerns. More importantly, the Direct Drive compressor can handle high RPM's and produce more air. Our older compressors had to be stepped down by way of a pulley, as they handled only half the rpm's that the engine generated. The result is a unit that can provide an extended operating depth for multiple divers.

 

The Third Lung 275, 325 and the 460 look a lot alike. What are the differences?


The 275, 325 and the 460 Direct Drive Third Lungs use different compressors and/or engines and have differing number of diver sets. (A set is the maximum number of divers that can descend to the deepest operating depth.) The 275-DD is a single piston system on a 2.5 hp Honda that can support 2 divers from 45 to 75 feet. Its main advantage is that it's only 32 pounds-- about the same weight as a single tank SCUBA rig. If the divers must carry a system over a great distance to get to their entry point, the 275-DD would be very attractive.

The more active hooka diver would be well advised to select the 4.0 hp Honda offered with the 325-DD. The 275-DD's 2.5 hp Honda engine is working at full capacity during a dive. A complete overhaul can be anticipated after 200 to 300 hours of operation. For many recreational divers, this number represents years of use; to some, a single season. The 325-DD has the same single piston system that the 275-DD has but is mounted on a 4 hp Honda engine. Like the 275-DD, it can support 2 divers from 45 to 75 feet. The 325-DD comes standard with setups for three divers (estimated depths for three divers is 15 to 30 feet.) It weighs 48 pounds. The advantage of the 4 hp engine over the smaller 2.5 hp engine is the 4 hp is actually quieter and works less hard, resulting in less engine maintenance and repair. Overhaul is anticipated from 500 to 800 hours of operation. The 325-DD is a good choice for the more active recreational diver.

The 460-DD is a double piston system and produces enough air for 4 divers, supporting them from 40 to 60 feet. It is also equipped for 4 divers. It uses a 5.5 hp Honda and weighs 55 pounds. The 460-DD is the workhorse of the Third Lung's line and is the perfect selection for the diver looking to get the highest possible performance from a hooka system.

  Hooka diving looks like snorkeling. Do I need to be trained?

True, Third Lung diving is almost as easy as snorkeling. The freedom of swimming unencumbered by SCUBA tanks will certainly remind you of snorkeling or free diving. Still, whenever you breathe air while under water, you are operating under a different set of rules. Training is required for everyone who uses the Third Lung. The training could be a traditional open water SCUBA certification course or a Recreational Hookah Diver course. The latter course was specifically designed for Recreational Surface Supplied Air Diving through the joint efforts of both Third Lung and the National Association of Underwater Instructors (NAUI). Courses involve about 30 contact hours and can be completed in as few as 5 days depending on available scheduling time for both instructor and students. With proper training and proper maintenance of equipment, hooka diving can be extremely safe. Third Lung has been accident free since it's inception in 1969.

  What about diving wrecks or in kelp?

Obviously, your use of a Third Lung to dive in overhead environments will be limited. Only slight penetrations are possible, and they should never be attempted without a back up air source. If you have evaluated a dive site and been able to determine that a Third Lung is appropriate, you can add additional hose lengths to increase your linear penetration range. Always be aware that hooka diving follows different rules than SCUBA; make certain that your air hose is free from potential entanglement or damage.

The Third Lung's advantage is that it is easy to find your way back out. Just pick up your hose as you exit from the overhead environment. The disadvantage is if the unit shuts down when the diver is exploring an overhead environment, the diver is without breathing gas and unable to make a free ascent. If you use your Third Lung in an overhead environment, you should always carry an alternative air source, such as the Third Lung egress system. Some situations would also lend themselves to placing a safety SCUBA rig in reserve, a common practice in any overhead diving scenario.

  Is it hard to pull a Third Lung along the surface while diving?

You might be surprised, but there is less water resistance in towing a Third Lung than in swimming with a full set of SCUBA gear. Considering that most Third Lung dives are shared between two or three people, swimming with a Third Lung is very easy. Conditions can increase the drag; windy days may make towing more noticeable. Many people simply drift dive on days when the wind is a bit strong, allowing the surface unit to gently tow them along through a dive.

  Will a Third Lung flip over?

The Third Lung rides well on waves and is even built to take a splash. If conditions are suitable for safe recreational diving, the Third Lung will handle the waves. Breaking waves near shore, however, are a different concern. A breaking wave in the surf zone or a large wake from a boat could flip the Third Lung unit. The user must seek safe operating areas as part of their pre-dive checklist.

If you are diving from shore, a hands-on transfer through the surf is essential. If you are diving from a boat, take special care in placing the Third Lung over the boat's transom and into the water. You could flip your Third Lung is it isn't lowered straight into the water. When in doubt, consult the owner's manual for proper launching procedures.

  What happens if the engine stops?

The dive is over.

Seriously, should the compressor develop problems during a dive, the diver might first be alerted of the air disruption when he or she no longer hears the gentle tapping created while the compressor is running. The tapping channels down the hose to the diver. If the divers do not notice the cessation of tapping, then breathing becomes restrictive at first, followed by an out of air situation. In either case, the diver must begin an immediate slow ascent to the surface. While free ascents from shallow depths are relatively easy, they are not without risk. Too fast an ascent can result in an pressure injury to a lung. Our recommendation is to have a back up Egressor Air Reserve System for each diver. The Egressor is standard in the XE package and is worn, hardly noticeably, in the small of the back It provides a very small back-up SCUBA reserve for emergency situations.

  How long are the hoses?

Third Lung hoses run off of the compressor unit in stages. First, a 10-foot heat hose cools the air as it leaves the compressor. A 60-foot common hose connects to the heat hose, leading to a split that supplies the 20-foot Diver's hoses. This system allows the divers to swim apart but keeps them within 40 feet of each other. All hoses use sturdy, reliable Quick Release Swivels that prevent air interruptions caused by hose kinks. The hoses may all be attached to each other in line, allowing a single continuous hose length of 100 to 140 feet.

  Why do you use a common 60-foot hose and then give each diver a 20-foot hose? Why not give each diver an 80-foot hose instead?

If that's the way the customer wants it, that's the way the customer gets it. No arguments, no additional cost. Not only do our customers prefer a single common hose leading off of the compressor, there's a solid performance reason behind the design. More hose does not create better performance. More hose equals more resistance (ore work for the compressor), more buoyancy (more lead hose required for the divers to wear) and more hose management (just a distraction that gets in the way of your fun). Another key point is that the diver's stay within 40 feet of each other. We think that it is a lot safer than being able to separate by more than 100 feet.

The single shared hose eliminates these problems. While others might tell you that separate hoses provide better breathing, be wary. We still dive the common hose without ever noticing increased breathing resistance, and we are happier that we have eliminated the hassles that additional hoses create. Here at Third Lung, we can configure the hose on your personal diving system any way we want it-- but we'd suggest that you try the single common hose before modifying your Third Lung to use multiple hoses from the compressor.

  Why do you say that divers can descend "from 45 to 90 feet"? Why the range?

Because different people breathe differently. It would be misleading to state that a system "truly" or "without a doubt" supports a certain number of divers to a definite depth. While we could quote one "best depth" rating, in the real world people breathe at different rates. For instance, the navy averages a diver's air consumption as falling within a cubic foot per minute (cfm) to 1 cfm. That's quite a difference. The mechanics of determining maximum depth are not complicated: the deeper you dive, the less air you get from the compressor. The amount you will receive drops by half in the first 33 feet. Four divers who breathe cfm each can go deeper than four divers that breathe 1 cfm each. That's why we use ranges. We want you to know before you buy.

  Why can't I use a surface reserve tank attached to the Third Lung for emergencies? Do I really need an egress system?

While we make bottles that attach to a Third Lung, they are not reserve tanks. Instead, they are accumulators designed for commercial application. A reserve tank is a back up air source, while an accumulator simply allows the diver to work a bit harder at times. Sometimes, with exertion, the diver can over-breathe the compressor's capability to produce air. The accumulator allows the diver a little extra air for short bursts. The problem is that the accumulator silences the tapping heard through the hoses (a situation that could be confused for an out-of-air emergency). The diver will not know the compressor has stopped unless they are communicating with a tender on the surface.

The Egress system, or some other pony bottle/SCUBA backup, is the safest insurance against an out-of-air emergency. The Egress system's Drop Weight CummerBelt fits comfortably around your waist and and provides you with both a weighting system and an emergency air source. Unfortunately, SCUBA tanks and regulators all cost about the same, be it for a 14 cubic foot Egress bottle or a full size 80 CF SCUBA tank. In spite of the cost, the Egress system is the best possible backup for your family during their hooka dives.

  Why don't I see more Third Lungs around?

Most likely because you don't dive in South Florida or the Caribbean. Here, in our backyard, the Third Lung is commonplace. You'll see them in use by recreational boaters an on live-aboard yachts. Some of the best lobster hunters in the Caribbean swear by their Third Lungs. On the west coast, recreational surface supplied air diving is relatively new.

 
Frequently Asked Questions | Operational Questions
  Why doesn't the Third Lung have an intake filter?

The intake filters that are supplied by the compressor manufacturer are plastic housings with only a piece of felt as the filtering media. They only filter dust, not carbon monoxide, water or carbon dioxide. They do not provide an additional safety margin or relevant benefit for either the diver or the machine while at sea. Also, the intake holes point directly up, where rain and water spray may easily enter. This position allows the felt to become wet or damp and may lead to interior damage to the compressor. The felt filters may also mildew if not changed, posing a potential health risk to the diver.

We take the felt filter housings completely off. We eliminate the dust catcher in favor of a cap that keeps rain and seawater from entering the compressor's air intake while reducing air intake restriction to a true minimum. The results show with our unmatched performance. We could leave the felt filter housing on-- if all we were interested in doing was saving a buck. Third Lung, however, has always spent that extra buck to do it right!

  How do you keep the exhaust fumes out of the engine?

Air is taken in high through the remote intake "snorkel/flag staff" The exhaust is low and exits the engine in the opposite direction being towed. The engine fan, designed to cool the block, further creates an air buffer between the exhaust and the intake.

Third Lung compressors are tested and meet the same grade air (E) required for scuba. Third Lung furthers the detail by adding a DRY snorkel cap to the remote intake.

  How much maintenance is required on a Third Lung?

Everything you need comes with the Maintenance Kit (standard to the XE). Hose the system down, following owner manual instructions. Attach the blower to the heat hose and dry the Third Lung quickly and easily. Next, use Corrosion X to lightly spray the engine. When everything has dried, put your unit away. The regulators should be serviced yearly by any full service dive shop. Follow the Honda owner's manual for maintenance requirements for the engine.

  I've heard that only a few compressors are designed for diving and that most are for construction purposes. Is your compressor designed for construction or diving?

Actually, neither statement is true. The manufacturers of oil-less compressors do not have a specific design for diving or for construction. How the oil-less compressor is utilized varies, just like any other light engine. For instance, a gasoline engine might be used to run a lawn mower, a go-cart, or in our case a Surface Supplied Air diving system. It's still the same engine. The same is true of the oil-less compressor. It has a myriad of uses. Please don't be mislead. None of the manufacturers of oil-less compressors used in the recreational dive industry certify these compressors as air breathing or for diving.

Third Lung adapts its oil-less compressors to withstand the harsh marine environment as well as to provide the same quality air as required for SCUBA (Compressed Gas Association Grade E). Don't believe claims that one oil-less compressor is a diving compressor while another is not. Ask for printed test results. It either meets the criteria for air quality or it doesn't. The proof is in the pudding!

  Why do you use plastic swivel fittings instead of metal fittings? Won't these break?

The metal fitting's swivel capabilities are limited at best. We used them for years until we developed the plastic Quick Release Swivel fittings. These QRS fittings are sturdy, will not accidentally disconnect and eliminate kinks with their swivel action. The plastic fittings have several additional benefits over metal fittings. Metal fittings will oxidize quickly in the marine environment. Third Lung QRS fittings will provide years of trouble-free use. While it is possible to break a QRS fitting, we rarely receive calls for replacements. If a QRS fitting does break, they are inexpensive and can be replaced with a simple wrench.

  Can the cases on your 275-DD and the 325-DD Third Lungs stand up to the temperatures, UV exposure, and possible rough treatment that one might expect on a boat?

We don't want to waste your time with all sorts of industry figures and jargon, but the 275 and 325 cases are manufactured of High Density Polyethylene (HDPE) and will provide a lifetime of protection to your Third Lung. The fact is, we've been using these cases for years. We haven't had to replace a single case due to cracking, U/V deterioration or melting. Any marketing claim by other manufacturers that materials like Cross-Link Polypropylene are superior to High Density Polyethylene is in the real world, simple balderdash. We stand on our successful record of real-world use.

  I'm concerned about room on my boat. How much space and weight does a Third Lung take up when stored?

Even the largest Third Lung units take up much less than the equivalent weight and space required for two SCUBA divers planning two dives. The 275-DD, with cover, measures 17 inches by 24 inches by 17 inches. The Textilene Gear Bag is 28 inches in length and 12 inches in diameter. The 275-DD weighs 32 pounds. The 325-DD, with cover, measures 17 inches by 24 inches by 17 inches. The Textilene Gear Bag is 28 inches in length and 12 inches in diameter. The 325-DD weighs 48 pounds. The 460-DD, is mounted on a round dish with a diameter of 18 inches. It is 15 inches high. The Textilene Gear Bag is 28 inches in length and 12 inches in diameter. The 460-DD weighs 55 pounds. With such compact dimensions, your Third Lung can easily stow on any size boat.

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