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Tech Air Pressure: Pressurized Reservoir Water Blaster Technology .:

Air pressure-based blasters are what changed the water warfare landscape in the early 1990s with the release of the Super Soaker 50. This article will explore the technology underlying this revolutionary water blaster and also go into how things have improved in more recent water blasters over the initial incarnation.
Air Pressure: Pressurized Reservoir Water Blaster Technology (Classic)


Air Pressure: Pressurized Reservoir Water Blaster Technology

Parts:

The pressurized reservoir water blasters' workings are comprised of seven (7) to eight (8) types of parts:

  • Pump Grip - where the user holds onto the sliding inner section of the pump
  • Pump Rod - the part of the pump that slides within the pump shaft
  • Pump Shaft - the outer casing of the pump that holds water
  • Nozzle - where water exits the water blaster
  • Check Valves #1 and #2 - one-way valves to control the direction of water flow from the reservoir to the pump, then to the nozzle
  • Reservoir - water and pressure storage compartment
  • Relief Valve* - allows excess pressure to be released safely well before other pressurized parts are likely to fail
  • Connective Tubing - joining the various parts together in a specific order

* Note: Not all water blasters have dedicated relief valves; water blasters, like the Super Soaker 50, did not need them since they used a pinch-trigger mechanism that would allow some water to escape out the nozzle if pressure in the reservoir got too high

Example Water Blasters:

The following are some examples of water blasters that use pump action water blaster technology:

The Water Blasting Cycle:

The steps involved when using this type of water blaster are detailed below. Differences between the Classic system and modern counterpart are noted.

Step 1: Priming

Air Pressure: Pressurized Reservoir (Classic) PrimingFor the classic system, before use, the reservoir needs to be removed and filled between 2/3 and 3/4 with water. If the reservoir is completely filled, stream performance will suffer significantly since there would not be enough space to build enough pressure for a longer blast of water. Once filled, the reservoir must be reattached securely so that no pressurized air or water escapes through the reservoir connection.

To prime the classic water blaster, the pump grip and rod should be extended out of the pump shaft, drawing air into the shaft. Check valve #1 will open slightly allowing air in.

Air Pressure: Pressurized Reservoir PrimingFor most modern water blasters, the reservoir is fixed and, instead, there is a fill cap that must be opened. Again, the reservoir should be filled between 2/3 and 3/4 full and the cap tightened so that no pressurized air or water can escape.

Akin to the classic water blaster, the pump grip and rod must first be extended out of the pump shaft. Some modern blasters  incorporate a check-valve-type set-up onto the pump rod end-cap that rests within the pump shaft instead of having Check Valve #1 as shown in the diagram. The differences will be discussed in some future article.

Step 2: Pressurizing

Air Pressure: Pressurized Reservoir (Classic) PressurizingThe key difference between pressurized reservoir water blasters and pump action, syringe, and trigger pump-based water blasters is that pumping these does not directly create the water stream. Instead, pumping pushes air into the reservoir in order to build pressure within. Once enough pressure is generated, opening another valve (i.e. pulling the trigger) will allow the pressurized water to exit out of the nozzle. Since increasing pressure is involved in the operation of these types of water blasters, the reservoir and internal parts must be built in a way to withstand these increase pressures. Moreover, safety/relief valves must be in place in order to prevent over-pressurizing which can result in part failure or, in worse cases, personal injury. In early models, the pinch-trigger valve assembly was a good choice since it served both as the trigger valve as well as allowing excess pressure to be relieved by opening when enough pressure was pushed into the reservoir to open the trigger automatically.

Air Pressure: Pressurized Reservoir PressurizingIn newer water blasters, pinch triggers are not as commonly found. Instead, pull valve or ball valve systems are more common since they are more durable and responsive. However, as these types of valves to not open even at high pressures, there is typically some form of pressure relief valve present as well on the internals assembly. It is the job of the relief valve to prevent the water blaster from being over-pressurized and possibly resulting in structural failure.

For both classic and modern pressurized reservoir water blasters, to build pressure within the reservoir, one simply pumps in air. Extending the pump out opens Check Valve #1, drawing air into the pump, while Check Valve #2 remains closed. Pushing the pump back into the pump shaft closes Check Valve #1 while Check Valve #2 opens, allowing air to be pushed from the pump into the reservoir. The number of pumps required to build good, functional pressure varies based both on pump volume, amount of air left in the reservoir to pressurize, and the maximum amount of pressure allowed by the system. For best performance, one typically pumps until the pressure relief valve engages or until it becomes difficult to pump and each additional pump does not feel like it is pushing any additional air into the water blaster's reservoir.

Step 3: Blasting

Air Pressure: Pressurized Reservoir (Classic) BlastingUnlike pump action water blasters, pressurized reservoir-based water blasters typically possess some form of trigger. Pulling (or pushing in some cases) the trigger will open the trigger/nozzle valve, creating a path for the pressurized water to exit via the nozzle. The force of the stream exiting the nozzle depends on a number of factors including the pressure difference between inside and outside the reservoir, the inner diameter of the connective tubing, the distance from the reservoir to the nozzle, the inner diameter of the trigger/nozzle valve, stream lamination, and the compression ratio of the nozzle, itself. Since both air and water can exit via the nozzle, in order to ensure that a stream is produced, the user must keep the intake hole or tube within the reservoir beneath the surface of the water within; if the pressurized air gets the opportunity to push through the tubing, since gas moves much more quickly than liquids, air will escape, resulting in much more additional pumping in order to regain operational pressurization.

Air Pressure: Pressurized Reservoir BlastingIn most modern water blasters, the pinch-valve trigger mechanism is replaced either by a ball valve or a pull valve. As neither of these other valves will open due to internal pressure alone, a separate pressure Relief Valve is commonly found elsewhere on the internals to prevent these water blasters from becoming over-pressurized and breaking. Otherwise, the same trigger operation and firing angle limitations exist as is found for the classic pressurized reservoir water blasters.

The requirement for keeping the intake port underwater results in something we refer to as a Firing Angle Limit. Simply put, the angles at which a pressurized reservoir water blaster can function properly is limited by the fact that at undesired angles, air will escape out the nozzle as opposed to water since water will move towards the ground regardless of which direction the blaster is pointed. Operational angles vary depending on the position of the intake port and the amount of water remaining in the water blaster.

Insights on this Technology

Air-pressure-based water blaster technology revolutionized the water warfare landscape. As was seen with the unprecedented popularity of the Super Soaker 50 in the early 1990s, the improved power, range, and performance of streams from these pressurized systems easily outperformed the typical trigger-pump-based, pump-action-based, and motorized water blasters that ruled during the 1980s.
Being manually pumped, these pressurized reservoir systems need no batteries to function. Since the reservoir stores pressure, once the blaster is primed, streams are created simply by pulling the trigger. Unlike pump-action water blasters, once pressurized, one actually can use many pressurized reservoir blasters single-handedly. The fact that only the trigger needs to be pulled allows much better stability and accuracy when tracking and targeting one’s opponents, vastly improving aim over the two-handed pump-action water blasters. Moreover, the amount of water that can be expelled by pulling the trigger is orders of magnitude larger than any trigger-pump-based water blasters with properly filled and pressurized water blasters able to empty virtually all their reservoir contents on a single trigger pull.

Of course, for this system to work well, the reservoir cannot be filled to the top. Without enough empty space left in the reservoir, there is not enough volume of air to be used to pressurize and subsequently push water out of the nozzle. Optimally, the reservoir should be filled to the 2/3rd or 3/4th level. As well, unlike pump-action water blasters that shoot on each pump, the number of pumps required before a pressurized-reservoir system can produce a solid stream is many more. The total number of pumps needed for optimal pressure depends both on the size of the pump as well as the size of the reservoir to be pressurized. As expected, as reservoirs get larger, more pumps become required to build pressure well. Particularly large pressurized reservoirs may take over 100 pumps to pressurize for which some may find a touch excessive (e.g. Water Warriors Drench ‘n Blast).

Granted, in order for the system to become pressurized, there can be no significant leakage of the pressurized air and/or water. Caps, reservoir bottles, and internals must be sealed securely, but not excessively which may lead to cracking of seals and/or plastic. In many classic water blasters, the entire reservoir was screwed into a holder that had a rubber gasket to help with the seal. Modern water blasters usually feature fixed reservoirs with reservoir caps that have an internal rubber gasket to help seal things closed.

Of course, one other issue with the fact these blasters are pressurized is the issue of over-pressurizing the internal system. If a relief valve or pressure release is not present, there is the chance that one can pump too much air into the system, causing parts of the internals to rupture and fail, resulting in leaks or even ejected pieces. On some models where the reservoir was only held in by a couple of tabs, damaged tabs could result in “Flying Tank Syndrome” where the tabs would fail and the reservoir launched into the air, propelled by the pressurized air and water mix like a small water-powered rocket. While there are some toy rockets that make use of pressurized air and water to launch (e.g. Super Soaker Rocket, Air Hogs Vector), having one’s reservoir launch during a water war is usually something a user does not want to do.

In terms of stream generation, the power of the stream depends on a number of factors:

  • the amount of water available: the more water available for the stream, the larger and stronger the stream can be
  • the pressure level: higher pressure means more force available to push the water out
  • the amount of pressurized air available: the greater the amount of air is pressurized, the more water that can be expelled before the pressure level drops significantly
  • the inner diameter of the tubing and nozzle valve: the larger the tubing, the easier it is for water to flow from the reservoir to the nozzle
  • the length of tubing between the reservoir and the nozzle: longer tubing slows water down more since  there is drag from the walls
  • the size and compression ratio of the nozzle: optimal nozzle geometry can significantly improve stream performance. Nozzle technology will be the subject of a different article.

Overall, pressurized reservoir water blaster technology represented a significant improvement over pump-action, motorized, and trigger-pump-based water blasters. On an interesting note, while the Super Soaker 50 was perhaps the most popular pressurized reservoir water blaster, it is actually not the first. Looking back, one lesser known water blaster known as the Cosmic Liquidator (1978) appears to be the first to feature pressurized reservoir technology. In its case, however, the reservoir was separate from the blaster part, connected by some tubing. Because of the length of connective tubing used, stream speed and performance are undoubtedly adversely affected. A pressurized reservoir, alone, is not enough to make a high performing water blaster. Perhaps the simplest of the pressurized systems, pressurized reservoir water blasters can offer solid performance for small-to-medium-sized water blasters. However, as the reservoir volumes increase, the number of pumps required to pressurize the system also increases. While one could theoretically also try increasing pump volume, in order to be able to reach desired operating pressures manually, the pump volume cannot be too large, otherwise most Users would not be able to pump enough air in as pressure builds in the reservoir. There is a fine balance between acceptable pump volumes and how much reservoir volume must be pressurized. When larger volumes are desired, the pressurized reservoir system reaches its usability limits and other types of pressurization technologies become preferred.

Advantages

  • Simplest of the pressurized technologies
  • Continuous streams with good power possible
  • Larger amounts of water able to be blasted out with a single shot
  • Trigger-based stream actuation improves aiming accuracy

Disadvantages

  • Reservoir cannot be completely filled; not enough air results in very poor initial stream performance
  • Must be pressurized (pumped) many times before a good stream can be produced
  • Internals must remain air/water-tight; leaks will result in lost pressure and reduced stream potency
  • Large reservoirs require excessive number of pumps to pressurize well, limiting how large a pressurized reservoir water blaster should be

 


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