Land speed record: Avoiding a big bang

One of our challenges has been the ports required in the HTP (high-test peroxide) tank. HTP is a strange substance. It can appear to be relatively stable – for example it will happily sit in a glass jar and appear to do nothing (actually it is always decomposing but at a very slow rate.) Add a few grains of desert dust, however, and it will start to gently fizz. It will get warmer and decompose faster. Add a lot of dust and you’ll have a rapid decomposition, which accelerates as the temperature increases – put this in a sealed environment and it will more than likely result in a big bang. 

 

It is for this reason that we need to get the HTP tank design right. Our current thinking is that the HTP tank itself will have a fill-and-drain port, an emergency water-in port, a nitrogen inlet and a large bore vent valve on the top of the tank, and of course an HTP outlet to the pump. 

 

The nitrogen inlet will maintain a positive pressure in the tank at all times to try and prevent dirt ingress. This will be just above atmospheric whilst the car is stationary, and at 1.69  kg/cm² once running. When the car is stationary, the emergency water port will always be connected to a water bowser, and a long flexible hose will be attached to the vent valve – the idea being that if the HTP starts to decompose, any gases given off will be vented away from the car and people working. If necessary the tank can then be flooded with water. The water will then be pushed out through the hose as relatively inert dilute HTP. The HTP tank will be monitored closely whilst the car is stationary and running, and we will be looking to ensure that the temperature remains steady.

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