Completed my build of a Mazzei Injector fertigation assembly (see pic
below).

Main Injector Assembly
Components:

• Mazzei 283 PP injector ($20.44)
• PVC Ball Valve (x3; $2.27 each)
• PVC Tee (x4; $0.60 each)
• ½ Male Adaptor (x2; $0.38 each)
• ½ Female Adaptor (x3; $0.64 each)
• PVC Union (x2; $2.56 each)
• PVC 90 elbow (x2; $0.28 each)
• Pipe bushing (x2; $4.18 each)
• Brass fitting ($4.74)
• ¼” NPT Pressure Gauge (100PSI; x2; $9.98 each)
• Smith-Cooper International 167L Series Brass Vacuum Breaker, Potable
  Water Service, Inline, 3/4" NPT Male ($10.60)
• DIG 3/4 in. Hose Thread Screen Filter ($6.68)

*all PVC fittings ½”

Filter Assembly components:

• 3/8-Inch Diameter by 1/4-Inch Clear Vinyl Tubing ($7.19)
• S-84 Mazzei Strainer ($7.95)
• SS Hose clamp (x2; $0.78 each)

Additional materials/tools:

• ½” PVC pipe (to make 2” connectors between fittings)
• PVC pipe cutter
• PVC Cement (all weather)
• Teflon tape
• Measuring tape
• ½" galvanized pipe clips

Some notes on my build:

I decided to build my assembly similar to
the Mazzei assembly illustration noted earlier in this thread. This increases the price a bit due to the
pressure gauges. The benefit is that you
can easily identify your inlet and outlet pressures. The outlet pressure must be dialed to a
certain pressure to regulate the water flow (gpm) suction of the Mazzei injector as noted above in the Mazzei performance table. Your gpm may need to change depending upon
your fertilizer type and concentration.

I also decided to go with all PVC
ball valves, even for the pressure adjusting valve (red valve in pic). I’ve noted several builds used the more
expensive brass gate valve but I was told by a plumber that brass gate valves
eventually leak on the stem below the hand wheel so it’s actually better to go
with straight PVC ball valves. The blue
valves allow me to completely shut down the Mazzei injector arm of the assembly
when I want to irrigate with only water.
The red valve is my pressure regulator which will allow me to adjust the
outlet pressure as needed.

I also used 2” PVC cemented connectors
with my assembly instead of going with threaded fittings. This was basically b/c my Home Depot didn’t
have all the fittings I needed in threaded form, so I went with straight slip
on adapters. If you can obtain all threaded
adapters that’s probably the best way to go as you can easily disassemble your
injector if necessary. Since I glued
mine together I can’t do that.

My injector also has a check
valve upstream and a filter downstream of the injector. This should protect fertilizer from
accidentally back flowing into my water system (via the check valve) and reduce
clogging of my drip irrigation adapters (via the filter).

I will be attaching this assembly
to a ¼” plywood board (using the galvanized pipe clips). This will allow me to easily hang it on my
fence during the summer and then remove and store it during the winter months
hopefully extending its lifespan.

All parts were purchased @ Home Depot except for:

• Mazzei 283 PP Injector (Kisco Sales)
• Mazzei S-84 Filter (Berry Hill Irrigation)
• Smith-Cooper ½” Check Valve (Amazon)
• 3/8” to ¼” Vinyl tubing (Amazon)

Please let me know if you have any
questions.

My kinda newb! lol Thanks smithmal, I'm researching such systems and may follow yours to a T (except I'll be using synthetic fertilizers for containerized plants in 5-1-1 soil-less mix). Any follow up as to how its working for you?

Also, did you put two of these in series to control pH as well?

Derrick,

Thanks for checking out my post. Unfortunately I wasn't able to assemble all the parts until almost the end of the growing season. But it's ready to go first thing when I start everything up this year.

In terms of using this in serial, I've seen posts in which this has been done, but haven't thought of doing it myself.

Smithmal

I think the acid can be added directly to the fertilizer harmlessly, but I'm not sure. I look forward to your updates.

Derrick

When I look at the picture, it appears that you've installed a Pressure Regulator at the outflow of your assembly and right after your "downstream" Pressure Gauge. Is that correct?

I have my irrigation lines set up with a Pressure Reducing Regulator and am wondering if I can install my Mazzei Assembly between my mainline from the hose bib and the Pressure Reducing Regulator at the assembly's outflow. Will that create the necessary pressure differential or is that dependent upon the ball valve (the red one , in your pic) in the assembly?