Differential pressure sensor based level meter

My project is based on a differential pressure sensor (in my case i used a piezoresistive sensor protected by a thin metal membrane). The sensor uses a standard piezoresistive film capable of sensing the mineral oil's pressure and compare it with the environmental one. If a difference of pressure occours the film bends and by doing so changes the resistance which is mesured by a electronic board (see renderings) which sends a digital signal to an external computer. The sensor is mounted inside a plastic holder which is mounted to the tank by a fixed stand. To mount the sensor you have to drill a 50 mm hole ( i hypothesized that the tank should be made of 1.5 mm metal sheet). Than you have to push inside the hole the fixed stand. The next step is to mount the sensor holder with the sensor in it. The positive fact is that the sensor can be replaced by just unscrewing 4 screws and everything should come apart easily. A rubber o-ring provides to all the assembly a good sealing. The sensor can be mounted in two different ways: - on the top of the tank but you will have to mount a pipe with a precise length to sense even the lowest liquid level. - on the bottom of the tank. This last choise presents one positive and one negative result: the positive one is that you don't need to mount any pipe and the negative one is that if you have to replace the sensor, all the tank need to be emptied first. The positive fact about the fixed stand (this part can be unmounted as well) is that the operator don't have to access the internal parts of the tank to install it and it is easy and fast to install and it can be a perfect way to upgrade a tank level meter by just drilling a 50 mm hole. All the parts are optimized to be formed by plastic injection. The assembly has a theorical weight of 50 gramms (without the pipe mounted). I came out with all the mesuring system (all the plastic parts) but the pressure sensor is an already existing tecnology and i only have explained how it works.