Separate pressure chamber (air pressure) water blaster technology is similar to pressurized reservoir water blaster technology in that both make use of the compression of air to pressurize water to create the water streams. However, unlike the pressurized reservoir system, separate pressure chamber systems typically push water into a fixed volume pressure chamber to create the pressure as opposed to pumping air into the reservoir (chamber) as in the pressurized reservoir system. Since one is pumping water (non-compressible) into a fixed, usually smaller volume chamber, the number of pumps required to achieve operational pressure remains lower and much more consistent.
The separate air pressure chamber water blasters' workings are comprised of seven (7) to ten (10) 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
- Connective Tubing - for connecting the other parts together in a specific arrangement
- Pressure Chamber - where pressurized air and water are temporarily stored prior to firing and creating the stream
- 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
Example Water Blasters:
The following are some examples of water blasters that use separate air pressure chamber water blaster technology:
The Water Blasting Cycle:
The steps involved when using this type of water blaster are detailed below:
Step 1: Priming
To prime, unlike for pressurized reservoir water blasters, the pump should be pushed in, forcing any residual air through Check Valve #2 and into the pressure chamber. While there are some nozzle valve differences between older and newer water blasters that use a separate air pressure chamber, these minor differences will not be discussed in this article since the overall operation remains the same.
For optimal performance, it is best to pre-pressurize the separate air-pressure chamber(s) with air before pumping in water. While not necessary, doing so usually improves stream performance throughout the duration of the shot. To pre-pressurize, the blaster should be held at an angle such that the intake in the reservoir is NOT submerged in water (Note: he usual direction is upside-down, but in some cases, one needs to consider the direction of the reservoir intake tubing if present. Sometimes, pre-pressurization is done most easily before the reservoir is filled with water). Once in position, the blaster should be pumped 10-30 times which will draw air in through Check Valve #1 as the pump is extended and pushed into the air pressure chamber via Check Valve #2 as the Pump Rod is pushed back into the Pump Shaft.
Step 2: Loading
Akin to pump action, syringe, and trigger pump-based water blasters, extending the pump draws water from the reservoir through Check Valve #1 into the Pump shaft. This, of course, requires that the intake within the reservoir is submerged under water.
Step 3: Pressurizing
Unlike pump action, syringe, and trigger pump-based water blasters, pushing the Pump Rod back into the water-filled Pump Shaft does not necessarily produce a stream right away. One can hold the trigger down when pumping water and get water to exit the nozzle, but in most cases, stream performance will vary wildly with each stroke. Instead, in typical use cases, water from the pump is used to build pressure within the separate air pressure chamber.
Pushing the Pump Rod into the water-filled Pump Shaft forces water through Check Valve #2 and into the separate air pressure chamber. As more water is pumped from the reservoir into the pressure chamber, the more the air within the separate pressure chamber is compressed, increasing its pressure and amount of stored energy. Since the volume of the pressure chamber is typically smaller than the reservoir and since water is mostly non-compressible, the number of pumps required to build adequate blasting pressure remains fairly consistent in a particular water blaster model.
Step 4: Blasting
As with pressurized reservoir water blasters, blasting is typically done through the activation of 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 in the separate air pressure chamber 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 pressure chamber, the inner diameter of the connective tubing, the distance from the pressure chamber 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 potentially exit via the nozzle, in order to ensure that a solid water stream is produced, the user must keep the intake hole or tube within the pressure chamber beneath the surface of the water within; if the pressurized air gets the opportunity to push through the tubing, since gas moves much more readily than liquids, air will escape, resulting in much more additional pumping in order to regain operational pressurization.
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 the separate pressure chamber will 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 firing chamber.
Other Flow Path: Over-Pressure
In virtually all modern water blasters, there is a Pressure Relief Valve that is designed to allow the pressurized water to escape in a controlled fashion to prevent over-pressurization and possible structural failure of the pressure chamber and/or pressurized connected parts. In older water blasters the Pressure Relief Valve allowed water to simply exit the internals and dribble out of the blaster. Most modern blasters, instead, incorporate the Relief Valve together with the Check Valve assembly, allowing water to flow back into the Reservoir instead of our of the blaster. This both saves water from being wasted as well as from other internals (and the User) from getting unnecessarily wet from a dribbling water blaster.
The Pressure Relief Valve works by using a pressure-calibrated spring that holds a plunger in a closed position. In the event there is more pressure in the Separate Pressure Chamber than what the spring is calibrated for, the greater pressure will force the valve open, allowing water (or air) to escape through the Pressure Relief Valve, preventing over-pressurization.
Insights on this Technology
Separate air pressure chamber-based water blaster technology was the next logical step forward for water blaster technology following the pressurized reservoir systems.
Being manually pumped, these pressurized reservoir systems need no batteries to function. Since it is the pressure chamber that stores the pressurized air and water, the reservoir can be completely filled (no room for air needs to be left) and the water blaster can even be over-filled/topped off after pumping water from the reservoir into the pressure chamber for the first time. Of course, there must be an air inlet into the reservoir, otherwise as water is pumped out of the reservoir, it will end up negatively pressurized relative to the surrounding air and may end up collapsing inwards.
As with pressurized reservoir water blasters, once pressurized, separate air pressure chamber water blasters can be used single-handedly (though many blasters that have a separate pressure chambers also tend to be larger and heavier when fully loaded, thus not easily wielded with one hand). 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 when properly pressurized.
Unlike pressurized reservoir water blasters that typically require more pumps to pressurize well, the fact that the separate air pressure chamber is typically more limited in size, much fewer pumps are needed to achieve good stream power. Of course, the drawback is that since less water is being pressurized at any given time, the amount of total shot time per blast is also reduced. That said, since less pumps are needed and the reservoir holds additional water, often enough to completely fill the pressure chamber 3-4 times, one is never without the ability to blast again for very long.
Of course, in order for the system to become pressurized, there can be no significant leakage of the pressurized air and/or water. Check valves, the pressure chamber(s), and internals must be sealed securely. Since the bulk of the pressurized components are internal and do not need the User to adjust, there is less requirement by the User to ensure parts are sealed. As the User typically only interacts with the pump, trigger, and filling the reservoir, so long as the water blaster was manufactured well, there is less chance in for a separate pressure chamber-based water blaster to have leaks due to the User not tightening parts.
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 functional, 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.
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: priming the separate pressure chamber with some additional air offers better stream performance, but also reduces the amount of water that can be pressurized before the Relief Valve activated
- 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 pressure chamber 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, separate air pressure chamber water blaster technology represents the logical evolution from pressurized reservoir water blasters. The Super Soaker 100 is the first stock water blaster known that makes use of this technology. There is a fine balance between acceptable pump volumes and how much pressure chamber volume must be pressurized. The internal set-up also paved the way for non-air-pressure systems to be developed.
- Simple air-pressure-based technology
- Continuous streams with good power possible
- Respectable amounts of water able to be blasted out with a single shot
- Trigger-based stream actuation improves aiming accuracy
- Reservoir can be completely filled, pressure chamber pumped, then reservoir topped off again to maximize available water capacity
- 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 pressure chambers require excessive number of pumps to pressurize well, limiting how large a pressure chamber on a water blaster of this type should be