the screen does not pop up help me

I suspect that the assembly comes apart by getting those blue end caps to move. See if you can squeeze them both together at the same time (maybe using a pliers), or using a flat-bladed screwdriver to gently pry them outwards. It would help if you had a picture that put more light on that particular part of the assembly.

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13 Meters x 12 Meters ==>> that is a huge garden ... and you want ALL the sprinklers to water it all at one time.. a few pix of your garden will help us help you ...... your flow rate is the least of your problems ... physics might be the bigger problem ... btw.. as to the supply line ...the smaller the pipe.. the slower the water moves thru it ... plz explain what you are growing.. and how you are growing it in this monster garden bed.. if you have lined out veg crop.. then drip is definitely the way to go .. and you should look into zones ... no need for electric switches.. water one or two zones a day ... cycling over a few days all the zones ... ken