I've built a small ucontroller based motorized valve which uses a stepper motor to drive a valve (small, 1/2" valve). The valve sits on a bypass loop which is connected to a rotary pump. The rotary pump produces 9bar of pressure and the valve on the bypass loop is there to lower this pressure when needed. I know this might sound a bit strange but it's a specific application, and what's more important, it's DIYed as I was trying to keep the costs to a minimum.At the beginning of the project I was planning to use a ball valve, but now I see it might be quite hard as the torque needed to move the valve is quite high. The motor is connected with the valve using gears and the high torque is ripping the gears from the spindles (held with grub screws) of the motor/valve. I was thinking of using a gate valve which needs very little torque to move, but read that it shouldn't be used for throttling. I was also thinking of using a needle valve, but those are quite expensive and I haven't got any guarantee that the torque is going to be low on them anyway.So the question is, what would you recommend for this application? The things I'm looking for:- quite small adjustment range (something I liked about the ball valve)- low torque- low price- food-safeIs it possible to get ball valves that have low torque and don't get stuck after a long time of no-use? Or perhaps lubricate them somehow?

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