Hot runner drops can be used with a needle inside. These hot runner drops are called valve gates.
However, the opening and closing of the needle can be done in different ways.
One way is to use air in order to move the needle and is implemented in the internal valve gate nozzle.
This pneumatic valve gated hot runner operates entirely without elastomeric seals, lubricants, or cylinder cooling.
It can operate at extreme temperatures of up to 400°C (750°F).