# Imperial Metric Threads?



## Susquatch (Jun 25, 2022)

My Hardi Sprayer is made in Denmark. Supposedly, it is metric from one end to the other. I needed a replacement quick connect for my gauge system. Which runs 6mm tubing from the spray boom to the tractor to monitor nozzle pressure. It cost me $29 for the quick connect at the Hardi Dealer. He told me he had no unions to fit the disconnect because it was metric. I said that was no problem because I could just make my own.

For the life of me, I couldn't figure out what the thread was till it dawned on me that maybe this metric sprayer has some imperial parts. Sure enough, the thread is 3/8 - 27 which is also known as 1/8 Straight Pipe. (not tapered like NPT).






This morning I decided to try and make a tip fitting for the Reilang Oil can I got on @Dabbler accolades. I need a tip that will reach down under the end of my cross slide.

I took the tip off my made in Switzerland oil can and measured it. It almost fits a 4.5mm 0.75 but jams after 4 threads. Guess what? It's a 10-32 thread on the tip.






Neither of these applications needed to be imperial and both are VERY European companies. It strikes me as very odd that both of them chose Imperial threads for their applications.

But it's no big deal. It's surely a lot easier for me to get my job done as a result. The sprayer fitting will be a slam dunk with off the shelf 1/8 pipe thread parts, and I'm thinking I'll make a little brass male/female elbow for the oil can tip. Something I can easily hold against the ball in the oil fitting.

Just sharing what I think is an odd discovery.

(Also using my phone to post photos with text between them to annoy @Chicken lights).


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## Chicken lights (Jun 25, 2022)

@Susquatch i agree completely with you, the imperial system is far superior to the metric system 

They do make a “metric o-ring” thread to pipe thread adapter, if you ever felt the need to redo it. Plus going from 6 mm hose to 1/4” hose you’ll gain 37% more efficiency....win win!


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## Susquatch (Jun 25, 2022)

Chicken lights said:


> @Susquatch Plus going from 6 mm hose to 1/4” hose you’ll gain 37% more efficiency....win win!



Good to know the adapter exists. This is not metric of course, just the tubing and the quick connect end is metric. 

There is no efficiency gain required. It's just a line to a pressure gauge that has no flow. It might have a wee bit of damping for large pressure changes but that disappears in seconds. Not only that but a little damping is a good thing in a system like that. I have no desire to watch a needle pulsing back and forth. 

For me, it's more important to have a quick disconnect that does not leak. Sprayers are leak monsters. As sprayers go, Hardi is a premium machine. I used to have a Calsa that was a complete fiasco from the first day I got it. It had a decent pump on it though.


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## whydontu (Jun 25, 2022)

the quick connect looks like G1/8 



			Vacuum Fitting Conversions – Standard Sizes for Threads


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## Susquatch (Jun 25, 2022)

whydontu said:


> the quick connect looks like G1/8
> 
> 
> 
> Vacuum Fitting Conversions – Standard Sizes for Threads



Excellent @whydontu! 

Here is what worries me about that......






My thread gauge suggested that 27 TPI was reasonable. This chart says 28 is correct. I can make 27 easily but 28 will be a challenge for sure. 

So much for using standard 1/8 straight pipe. 

Since it seals with an O-ring, I'm thinking I can shorten the thread to make it fit enough to seal at the O-ring without deforming the threads more than necessary. 

Thoughts?


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## whydontu (Jun 25, 2022)

G tap is 55*, NPT is 60*. Depending on which direction you’re going, it is possible to get them to seal and hold. Male G to female NPT will work if the o-ring has a smooth surface to seat against on the NPT side. There’s only maybe four or five threads engaged. 

Lots of pipe fitting manufactures make g to npt adapters, Parker, Swagelok, ByLok, Ham-Let.


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## Susquatch (Jun 25, 2022)

whydontu said:


> Lots of pipe fitting manufactures make g to npt adapters, Parker, Swagelok, ByLok, Ham-Let.



This just keeps getting more and more messy. 

I think the adapter is my best bet. I'm not keen on having any leaks. 

I may also see if anyone makes taps and dies for G. 

I can see now why Hardi didn't go metric with this connector. Can you imagine a metric version of this G thing too?


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