FCOA makes an effort to make diving available for everybody. When it comes to scuba diving, we need technical equipment. By knowing how to do simple repairs ourselves we can save time and money getting things fixed. By knowing how to test secondhand equipment, we can buy gear at a fraction of the new price.
For all equipment counts that salt crystals deteriorate them. Your best of to wash your gear right after the dive before the salt starts crystalizing. It's best to submerse the equipment in fresh water and leave it there for a while. The colder the water the longer it takes for salt crystals to get dissolved, 3 to 5 minutes should do it.
Another factor that deteriorates dive equipment is sunlight so dry your equipment in a shaded and cool area.
REGULATORS
Judging secondhand regulators
Before buying a secondhand regulator, it be good to do the following tests.
- Before connecting the regulator suck from it and listen for air leaks.
- Put 200 bar on the regulator and listen for air leaks, or even better sponge the regulator with soap so bubbles will appear when there is a free flow or hold the regulator under water to be able to see every single leak.
- Breath from both the regulators to see if breathing feels effortless. It's normal for regulators to make a loud zooming sound when breathing from them above water. This is the membrane that vibrates, once you are under water, the water pressure against one side of the membrane will stop it from vibrating.
Causes of regulator free flow
Some reasons a regulator can start free flowing
- A grain of sand prevents the spoon from closing completely. Press the purge button and tap the demand valve, or without pressure, wash the demand valve while pressing the purge button.
- A salt crystal prevents the spoon from closing completely. Submerse the regulator in fresh water to allow the salt to get absorbed.
- A calcium deposit prevents the spoon from closing completely. Submerse the regulator in vinegar for 5 minutes to melt the calcium deposit.
- Due to impact the spring tension has changed. Open the regulator and adjust the nut that regulates the spring tension.
- The first stage has a warn seating. Due to this the middle pressure (usually around 10 bar) slowly goes up to 11, 12, 13 bar. The demand valve is designed to let out this over pressure. If this is the case then there is nothing wrong with the demand valve, it just gets too much pressure. The seating in the first stage will need to get replaced. You will know for sure that this is the case by connecting a middle pressure meter to the first stage.
- The first stage can also cause the middle pressure to rise due to salt or calcium deposits. Before starting a repair take the hoses of, place it 5 minutes in Vinegar, then 5 minutes in fresh water, then blow out all the water and attach the hosed again to see if this solves the issue.
Changing SPG (Submersible Pressure Gauge) skiffle's and Second stage Orings.
Since SPG's and second stages can turn there for the O-rings involved with the turning wear down faster than most other O-rings in the regulator and then they start leaking. To change that O-ring you have to take the SPG out of its rubber housing. This is only possible after you warm up the housing with hot water. Best always use the exact tool sizes to minimize scratching. A dentist hook can be handy to take out the O-rings that you want to replace.
BCD's BUOYANCY CONTROL DEVICES
Tips when buying second hand
- Inflate them completely and make sure they stay inflated
- Over inflate them and check if the overpressure release properly opens and closes.
- Make sure the nipple of the inflator fits your inflator hose, beyond the standard fitting there are some nonstandard fittings on the market.
- Once the Inflator hose tears out of the jacket it often is no longer worth reparing. Most repairs will soon leak again.
Common repairs on BCD's
- The inflator is self-inflating: Are you able to pull back the inflator button? Bath the inflator in vinigar, the free flow can be caused by calcium deposits, and they disappear in vinigar. If this does not help, then open the inflator. Many inflators have a same push valve a car tiers have, if that is the case take out the old one and replace it with the new one. These valves are most economic to get at a tier shop; they often give them for free.
- If the overpressure release goes off too early then unscrew them, stretch the spring a bit and put it back, now it should hold a bit more pressure before blowing off.
- Small leaks can get glued with specific glues like aqua seal.
TANKS
In most countries tanks need to get tested every 5 years. After testing they get the testing date stamped on the neck. To find economic places to test your tanks, follow the trail where Oxygen tanks come from either at a wilding shop or hospital. Oxygen tanks also need to get tested every 5 years, so oxygen suppliers can tell you where they do their testing a minimum cost. Some dive centers also offer tank testing, usually they charge a bit more for it because then they prepare and transport the tank for you but once it returns you can pick it up ready for use.
To test tanks for leaks on the valve or the neck seal, you can either spray them with soap water, it will then bubble if it has a slow leak. Or you can place them under water to see if air bubbles out.
Tanks can be made out of steel, aluminum or carbon fiber. Steel tanks hare heavier than aluminum. Under water divers like that because then they need les weights on their weight belts. Steel tanks can corrode from the inside and the outside. This can look alarming, and it should get addressed, but regardless steel tanks are the strongest and have the longest life span. As long as they pass their periodic tests they are good to use.
Valve to Cylinder miss match: If you buy a new tank valve assure that the valve is made for your tank. Accidents have happened where wrong valves seem to fit properly but pop out during compression causing an explosion.
SURFACE MARKER BUOYS
To test them, fill them with water and see if they drip. They should not.
DIVE COMPUTERS
Possible issues:
- Dive computes have a pressure sensor to interpret the depth, if it fails you either get no depth reading or an erroneous depth reading.
- After changing batteries of a computer, the seal might leak. In the better dive shops, they can test the computer in a little pressure chamber with fresh water. You can't see water leaking in, but once reducing the pressure you can see bubbles coming out. Then there is still a chance to reopen the watch, dry it and seal it again. Yet if it is salt water the computer usually cannot get saved. By only using a dive computer for diving and not as a regular watch the battery will last longer.
- Software errors. Make a habit of knowing your dive profile by looking at a dive planner so that when your computer gives wrong information you will notice it.
- Dive Computers can be in mountain modes, or nitrox modes, this changes the NDL (No Decompression Limit). If you wish you completely rely on the computer, then make sure to read the manual.
- Freediving mode versus Scuba mode. When you freedive with your computer in Scuba mode, it will give you speed warnings on the way up and it will think you have skipped your safety stop. It sometimes locks out for 48 hours before it can get used again.
- When buying a secondhand computer ask the seller to film it while diving with it, a one minute video of it operating at the depth of the dive can provide you with a lot of information:
UNDER WATER CAMERAS
- It is safest to test the housing without the camera in it. Just fill it with tissue and after a dive check if the tissue is still dry.
- For cameras in particular it good to soak them in fresh water right after diving in salt water even before water can start evaporating and before salt starts crystalizing.
