[Syphonics]

How do i slow down the pneumatic actuator stroke speed? Do i need a timer valve or do i need special actuator?
Can a single acting actuator slows down?

[Al_The_Man]

Flow control valve.
You can get uni-directional or bi-directional, adjustable.
Al.

[ViperTX]

As Al pointed out...that is how is should be done....you can also experiment with an inlet valve that you use to control the volume of air going to the actuator.

[One of Many]

Yes, with a single acting cylinder you can control the flow in different ways depending which direction the reduced speed is needed.

Here is an adjustable flow control you should be able to find in your area of the world.
Like this style

This will go between the valve and the cylinder. It is adjustable in one direction and free flow in the other. So, you can control air going into the cylinder or air coming back out of the cylinder. This only allows control in one direction or the other depending on how it is installed. This type of speed control does work, but can leave the cylinder a bit springy and is not as stable as a double acting cylinder. Small volume cylinders may not be controllable due to pressure delays.

If you need independant control, you might consider changing to a 5way valve, double acting cylinder and use flow controls on the exhaust side of each valve port.
Like this style

Or you could place one of these directly on the ports of a double acting cylinder and use exhaust mufflers on the 5way valve.
Like this style

A simple in-line needle valve may work to, but again it will restrict flow in both directions and may not be a positive solid stroke. Acting a bit lazy in both directions.
Like this style

DC