Drip Tape Questions.

[Hawkins]

So I got 3.6mm fittings for the start of the drip tape, does that matter, or should I get 7mm and why? I just added what was recommend in the kit.

 

[Rajun Gardener]

Pressure gauges are there when you first run it to make sure everything is working correctly. If you exceed the rated PSI it'll blow out, and if you've got dripline buried under row cover, that's bad. With pressure gauges the first time it's fired up, you can have someone with their hand on the off valve while you keep an eye on the gauges as pressure ramps up.
 
After that, it's not so important, but when you are first getting everything set up, it is.

 
 
I still don't understand how you blow lines when the regulator is the first thing connected to the water source.
 
Maybe you're setting it up totally different but still one regulator should work on the system as long as your pump can keep up with volume.

 

[TrentL]

 
 
I still don't understand how you blow lines when the regulator is the first thing connected to the water source.
 
Maybe you're setting it up totally different but still one regulator should work on the system as long as your pump can keep up with volume.

 
No regulators only work within a given range, and there's a LOT of other factors that will screw with pressure. You can't just "trust" that you're getting optimal pressure. That's what gauges are for. 
 
Example, I ran a 2" big fat pipe 480 feet across nearly flat ground (a whopping 4' of rise), and .. got no water out of it. Turns out head pressure on 480' of flat tube was enough friction to keep water from so much as trickling out at 60 psi. Plugged a gauge in at a few spots, covering holes with goof spots, figured out what was going on. The event was capped off by a big BOOM and a blown flattube. 
 
My 2" regulator also wouldn't work unless I was pushing a good 25 gpm through it. Anything *below* that and it didn't cap pressure at all, my dripline would climb towards 60psi and blow out. So I had to plug in a LOT of dripline to move enough water for a 2" regulator to work. Sure, says 12PSI, but you gotta be within the range for it to work. Anything over or under that and it don't work right, doesn't limit the pressure. Big problem is when my well couldn't keep up (started to run dry, blowing air), it couldn't move enough gpm through. This led to a pressure spike downline, because GPM dropped below the min threshold to make it regulate pressure. 
 
With pressure loss over distance, depending on type of pipe, rise or fall, and length of piping, along with length of drip tape and emitters, with the cost of everything added up on a larger scale, you'd be foolish not to drop some $5 plug in pressure gauges here and there. 
 
Another example is down slope, I had my end lines blow out because - sure, pressure at the regulator was 12psi, but by the time you get 15' lower, suddenly it is much, much higher. My driplines at the top of the slope were 15 PSI, but a hundred foot down a gentle gradual slope? Over 30 PSI, and rupturing once in a while. 
 
Bottom line is you really have no idea what is really happening inside the pipe without a gauge, and sometimes what your regulator is rated for doesn't match reality of what is hitting the start or end of line.