Expromizers, expromizers, expromizers

[Intuthu Kagesi]

Reminiscent of the little engine that could, only they didn't! ... buuuuuuuuut they can ... with a minor modification.

The V5 comes closer to my version of loose MTL than the V4, so lets look at it first;
Some measurement and math on the air flow revealed that the V5 top air flow had a total area, (wide open), of 13.7854 square mm ... DL territory!

The junction between the chamber airflow and deck, a total volume of 4.7124 square mm, (into RDL territory), and;

The center screw also has some restrictions at 1mm x 4 = 3.1416 square mm feeding a 1.5mm centre hole with an area of 1.7672 square mm, which in turn feeds the undercoil holes with a volume of 2.3562 square mm.

To correct the center screw bottleneck, and move it to under the coil, we would need enlarge the centre hole of the center screw, to give us an area of at least 2.3562 square mm, which equates to 1.7321mm ... I'll use a 1.8mm drill bit, and err on the side of more air.


Anyhooooo ... on to the V4 ... so here they have a top air flow area, (wide open), of 4.7124 square mm, (roughly a third as much air as the V5).
The junction between the chamber airflow and deck, as with the V5, a total volume of 4.7124 square mm, SNAP ... and;

An undercoil volume of ... wait for it ... 5.0265 square mm ... so where is the problem? ...

Just like the V5 ... It's the flippen "center screw with airhole", which is slightly more restrictive than the V5, at 4 x 1mm, (3.1416 square mm), into a 1.2 mm center hole (1.131 square mm!)

So to "convert" your V4 to a V5, you would need to drill this out carefully to 1.5mm, from 1.2mm, or ... to make it really perform;
Drill it out to 1.8mm as per the V5 modification above.
This would allow a greater "spread" of air at lower air flows, increasing saturation, whilst allowing them to function in the RDL space simply by adjusting the top airflow.




Interesting little factoid ... The Ver.3 had a 2.6mm hole under coil, and was a great MTL AND RDL Atty, until Todd decided in his great broscience / non scientific way, to tell the world that 2.6mm was too big ...
Do these reviewers even know what fluid dynamics is, or bother to take into account ALL other restrictions in an Atomiser, as underneath the deck, underneath the 2.6mm hole, was a 2mm restriction ... yes you guessed it, a flippen "Center Screw with Airhole" ... not to mention that air is being pulled NOT pushed ... that there is a vacuum created when you suck, which is decidedly different from air being pushed into the airflow, anyhoooo ... all this prompted the aforementioned shifts above, which thankfully can be easily corrected, to bring the Expro back into the domain of outstanding.

 

[Intuthu Kagesi]

And the testing is in ... For those apprehensive about doing this modification, that would prefer to have their V5 perform like a V4, you simply restrict total air flow up top to "one hole", (1mm or 0.7854 square mm), or two holes at 1.5708 square mm, however;
For those wishing to unleash their Expromizers, (Version 4 and 5), I can highly recommend it, to which I settled on a 1.7mm hole as apposed the proposed 1.7321mm, remembering that you can still restrict total air flow down to "one hole", (1mm or 0.7854 square mm), on the top air flow

 

[Intuthu Kagesi]

More on Air Flow

The flow of fluid through a pipe is influenced by several factors, including the diameter of a pipe. In general, fluid flow tends to be smoother and more efficient in a larger diameter pipe compared to a smaller diameter pipe. This is because larger pipes provide less resistance to flow, resulting in lower friction losses.
When considering a system with a large-to-small diameter transition versus a small-to-large diameter transition, (ie. restricting air flow at the inlet of an atty vs. the chamber vs. at the mouthpiece), there are a few points to keep in mind:

Flow generally slows down when transitioning from a larger diameter to a smaller diameter.
There will be an increase in pressure due to the reduction in cross-sectional area, but the flow velocity will decrease.

Flow speeds up when transitioning from a smaller diameter to a larger diameter.
There will be a decrease in pressure due to the increase in cross-sectional area, and the flow velocity will increase.

It's important to note that the specific characteristics of fluid flow in a pipe system depend on various factors, including the fluid properties, the overall system design, and the intended purpose of the system. Engineers use principles of fluid dynamics and pipe sizing calculations to optimize the design for the desired flow rate, pressure drop, and the total system efficiency, with gradual transitions in pipe diameter, (rather than abrupt changes), preferred to minimize turbulence and pressure losses. Additionally, the Reynolds number, which characterizes the flow regime, becomes important in predicting whether the flow will be laminar or turbulent.

Then to Venturi's
A Venturi tube, or simply a Venturi, is a device designed to measure the flow rate of fluid in a pipe. It is based on the principle of Bernoulli's equation, which describes the relationship between fluid velocity and pressure. The Venturi effect, named after Italian physicist Giovanni Battista Venturi, is the phenomenon that occurs when fluid flows through a constricted section of a pipe.

The basic principle of a Venturi is a tapered constriction in a flow path. This constriction causes the fluid velocity to increase as it passes through the narrowest part of the tube, and if an orrifice, (or saturated coil in the case of an Atty), were present at this narrowest part, a vacuum would be created.

According to Bernoulli's equation, there is an inverse relationship between fluid velocity and pressure. As the fluid velocity increases, the pressure decreases, and vice versa.
In the Venturi tube, as the fluid accelerates through the narrow section, its velocity increases, resulting in a decrease in pressure, by measuring the pressure difference, the flow rate of the fluid, (gasses are seen as a fluid for purposes of fluid dynamics), can be calculated using the Bernoulli's equation and other relevant fluid dynamics principles.

The humble Venturi is often used in applications where accurate measurement of fluid flow is crucial, such as in water and gas pipelines. It provides advantages over other flow measurement devices by minimizing pressure losses and maintaining a relatively low permanent pressure drop. In addition to flow measurement, Venturi tubes are also utilized in devices like Carburetors in internal combustion engines, where they assist in the mixing of air and fuel for combustion, and in our case, in Attys, where they assist in the mixing of air and eliquid for vapour production.