The PVC inflatable boat is a complex engineering structure where each element plays a critical role in crew safety, and at first glance it may seem that the bulk of the load is carried only by the solid material of the cylinders, but it is the small parts that often determine the final life of the product. discharge-valvewhich prevents the rupture of the shell with a sharp increase in temperature.
On a hot summer day, the air inside the cylinders expands, creating excessive pressure, and if this process is not controlled, the boat can burst right on the shore or, worse, on the water. discharge-valveIt automatically releases excess gas when the pressure reaches critical values.
Understanding how this mechanism works is essential for every owner of a boat, and ignoring its condition or misconfiguring it can lead to an emergency, so it is important to know how it works and when it requires intervention.
Principle of operation and mechanism design
The pressure-emitting valve design seems primitive at first, but it has a high reliability, and inside the shell is a spring-loaded membrane or rod that covers the outlet, and when the internal pressure in the cylinder exceeds the threshold, the spring compresses and the gas begins to come out.
There are two main types of such systems: built-in in the main intake valve (most often type). Bravo or BayardThe built-in models have two protection stages: the first, which emits a small amount of air, and the second, which is emergency, which is triggered by significant overheating.
It is important to note that trigger-point It is usually set by the manufacturer to a certain value, for example, 250-300 mbar. Change this setting without special equipment and understanding the physics of the processes is not recommended, as this can upset the balance of rigidity of the structure.
⚠️ Warning: Never attempt to seal or block the etching mechanism, even if the boat appears "slightly pumped" The lack of ventilation when heated in the sun is guaranteed to cause the seams to rupture.
Removable valves are often found on premium boats or high-pressure inflatable floor (HPD) models, which allow pressure relief to be spot-on without affecting the main air chambers, which is especially true for complex multi-chamber systems.
Technical nuances of spring groups
Inside the valve, a special spring of stainless steel is used, which does not lose elasticity during prolonged compression. Some cheap Chinese counterparts use conventional steel, which eventually rusts and sticks, no longer performing its function.
Main causes of operation and failure
Boat owners often experience a valve that starts poisoning the air for no apparent reason. The first and most common cause is a simple overheating in the sun. Even if you pump the boat in the morning at +20°C, by lunch at +30°C and the scorching sun, the pressure inside can rise by 30-40%.
But there are mechanical causes of malfunctions, and if you get sand, fine dust, or salty crystal crumbs under the sealing gum, it breaks the sealability. valve-membrane It cannot press tightly against the saddle, and air comes out constantly, even at normal pressure.
Also consider the natural wear of materials: rubber seals tan over time or, conversely, become too soft, losing their properties, this is especially true for boats that are stored in inadequate conditions or operated for more than 5-7 years without revision.
- 🌡️ A sharp increase in ambient temperature and direct heating of cylinders by sunlight.
- 🏖️ The entry of abrasive particles (sand, salt) into the working zone of the locking mechanism.
- 🔧 Mechanical damage to the rod or deformation of the valve body during careless transportation.
- 🕰️ Aging of rubber seals and loss of spring elasticity.
If you notice that air etching is constant, you need to do a diagnosis, sometimes just rinse the mechanism with clean water, but in some cases you will need a complete replacement of the node.
Constant air venting in the shade at normal pressure is a sign of a seal failure or contamination, not the normal operation of the system.
Diagnosis: When the valve is working normally and when it is not
Distinguishing the normal operation of the system from the breakdown can be difficult, especially for beginners, it is normal to short-term hissing of the valve in hot weather or after active rowing / motor movement, when the cylinders are heated from friction against the water and the sun.
Anxiety should be struck if the characteristic sound of air exit is heard immediately after pumping the boat indoors or in cool weather, in which case, most likely, the leakage is disturbed. lock-pieceYou can check this by applying a soap solution to an open valve (without a cap).
If bubbles appear that do not stop after a few seconds, then the valve needs cleaning or repair, and it is also worth checking the pressure with a pressure gauge: if it drops faster than 0.01 bar per day at a stable temperature, the system is leaky.
| A symptom. | Probable cause | Action |
|---|---|---|
| Short-term hissing in the sun | Air expansion | No intervention required |
| Constant hissing in the shade | Sand under the membrane | Washing and cleaning |
| Whistling air when pressed | Under-pumped balloon | Add pressure to the pump |
| Visually visible damage | Mechanical wear and tear | Valve replacement |
It's important not to confuse the discharge valve with the main inflatable valve. Some models combine them, but they have different modes of operation, the main valve holds the pressure, and the discharge valve discharges the excess.
Instructions for maintenance and cleaning
Regular maintenance extends the life of the boat, and you'll need clean fresh water, a soft brush, and perhaps a silicone-based lubricant to do the work, and before you start any treatment, you'll need to deflate the boat completely, or at least keep the pressure down to a minimum.
First, twist or remove the outside of the valve, if the design permits, carefully examine the insides for sand, pile or insects, and often it is the stuck grain of sand that prevents the valve from closing completely.
☑️ Planned valve maintenance
Washing is best done under a low water pressure, carefully removing contaminants. If seawater is used, be sure to wipe the knot with fresh water to prevent corrosion of the metal parts of the spring.
Once cleaned, reassemble the valve and test it, and if the hissing stops, the problem has been solved, and if the situation recurs, you may need to replace the sealing ring or the entire assembly.
⚠️ Note: Use only silicone lubricants to lubricate moving parts. Petroleum products (WD-40, engine oil) can destroy the rubber and glue used in valve installation.
Replacement and installation of a new valve
If cleaning didn't work, or if the valve body got cracked, the only way out is to replace it, which is a more complex procedure, requiring precision and a special glue for PVC. You'll need a new valve of the appropriate diameter and type of thread.
The process begins with the dismantling of the old element, using a special key (often bundled with a boat or a pump) that twists the inside, the outer part (response) is usually glued to the cylinder and requires careful peeling or cutting.
The surface of the PVC around the hole needs to be cleaned with fine sandpaper and degreased, and the glue is applied to both surfaces, the fabric of the boat and the flange of the new valve, and after drying the first layer, the second layer is applied, and the parts are joined.
Use a two-component polyurethane adhesive for PVC. It provides the best adhesion and elasticity of the seam, which is critical for the movable parts of the boat.
It is important to ensure that the valve is pressed evenly during drying, using a sandbag or a special load, and the time for complete polymerization of the glue is 12 to 24 hours, after which pressure tests can be performed.
- 🛠️ Carefully clean and degrease the surface around the hole before sticking.
- ⏳ Follow the time intervals of drying glue specified by the manufacturer.
- 🌡️ Work is carried out at a temperature not lower than +15 C and low humidity.
- 🔩 Use only original or certified compatible valves.
After installation, be sure to check the leakproofness with a soap solution. discharge-valve No air should be allowed to pass either side at working pressure.
Valve selection: compatibility and types
When buying parts, it's important to consider compatibility. The market is full of modifications, and there are almost no universal solutions, the main differences are in the diameter of the thread, the height of the rod and the type of attachment to the cylinder.
The most common type of valves Bravo (Italy/China), which are installed on most mid-range boats. Springer Specialized models for high pressure bottom (Hypalon/PVC).
When choosing, consider the material of manufacture: brass and stainless elements are preferred over plastic, because they better tolerate mechanical stress and temperature changes. Cheap plastic can crack in severe frost or impact.
Don't skimp on this element. The cost of the valve is incommensurable to the cost of repairing the cylinder or the risk of life on the water. A quality mechanism will last the entire life of the boat without the need for replacement.
Can you operate a boat if the valve is jammed in the open position?
Operating is possible, but it's very inconvenient. You'll have to pump the boat constantly, because it's going to lose pressure quickly, but it's safer than jamming in a closed position, which threatens to burst the balloon in the sun. In any case, it's better not to delay repairs.
What is the difference between a PVC boat valve and a SUP board valve?
The main difference is the operating pressure: SUP boards are pumped to 1.0-1.5 bar, whereas boats are usually up to 0.25-0.4 bar. Springs in the bord valves are stiffer. Installation of an inappropriate valve will either lead to constant etching or to rupture of the shell.
How often should the squirt be changed?
The life of a quality valve is 5-10 years, but rubber seals may require replacement earlier, after 3-4 years of active use, and regular prophylaxis and lubrication with silicone significantly prolong the life of the unit.