Week 12 – Design development on the Water Container

Let’s recap on our initial design for Imp Bot’s water container!

We planned to use a 12V solenoid valve to allow water to flow into a plastic bottle as shown below:


(The metal clamp ring is used to clamp the bottle and valve together tightly)


What is a solenoid valve?

A solenoid valve is an electromechanically operated valve. The valve is controlled by an electric current through a solenoid: in the case of a two-port valve, the flow is switched on or off; in the case of a three-port valve, the outflow is switched between the two outlet ports. (Wikipedia, 2016)

12V Solenoid Valve

The solenoid valve is initially in its de-energized state. When it gets lowered down to the designated depth, a voltage is applied across the two terminals of the valve and the solenoid attracts a metal piece upwards. The hole/mouth is then opened and allows water to flow through to the other end of the valve (where the bottle is). After 10 seconds, the electromagnet de-energizes as the voltage gets cut off. Now, the water is trapped and stored in the plastic bottle, unable to leak out.

On the 4th of January 2016, Monday, we went down to the pool side to test out the solenoid valves!


P.S. We guess this experiment was rather unorthodox as we just lowered the solenoid valve down into the water, without any prior waterproofing of the cables! In general we realize this is bad practice, but due to the solenoid valve only requiring 12V and the power supply having an in-built circuit breaker, the current would never be high enough to electrocute us, even if the pool was considered to be “live”.


We tested out three solenoid valves at different orientations (horizontal & vertical) and different depths in the water (max. 0.8 metres). However, we observed that no water flowed into the valves. We tried to troubleshoot by dismantling it to check whether the problem lied in the internal mechanism. Yet, everything was perfectly fine.

Despite us being unable to continue to use this device, we moved on and did even more research on water sample collectors. We stumbled upon an idiosyncratic invention known as the Niskin Water Sampler (as shown below)!


Researchers and scientists use this sampler to collect water from rivers and lakes for experiments and testing of the water qualities at different depths.

Due to the limited time and budget we had left, we simplified the original design of the Niskin Water Sampler to our own design as shown below:


Materials needed: (Obtained from Sun Hee Hardware Store at Clementi)

  1. Nylon String (2-3m)
  2. Toilet Plunger
  3. Rubber Stopper
  4. Aluminium lever
  5. Aluminium handle
  6. Elastic rope
  7. 2 eye bolts with nuts
  8. PVC pipe reducer
  9. M4 x 16mm screws and M4 nuts

After getting all the materials we needed, we went back to the workshop and fabricated it. And then… it’s time to test it out!

And it works!

We have finalized our current design for our prototype as shown below:


Hwee Peng


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