Got the flow unloader

Thought I’d go ahead and start a new topic.

Finally got over to Southside and Russ hooked me up with this.

I noticed it says ‘K1’ and asked him if he had the ZK1, he said it’s the same thing. Is this what I need?


It’s the same, when I was looking at them I think I read the difference was between US/Europe using “Z” or not but virtually identical for every other spec. The only thing I wish I would have realized/thought about is that you can get them with 1/2 or 3/8 outlet which would have reduced the number of adapters and potential leak points but it’s been fine so far.

I will be getting this soon. Let me know how it goes. Did the block come with or separate?

make sure you run a 5/8 bypass hose

5/8”? Good to know.

The block was separate.

5/8!!! Anything above 1/2" kept my unloader surging/cycling… dropped down to 1/4" and all is well… but I’m also running a 5 gpm rated pump so that may make a difference from the big boys some of you run.

You running a zk1? Or a 7

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It’s a zk1

Mine came with a sticker on it to run 5/8, I think. I’ll look tomorrow. Maybe it was 1/2. I was running so many hoses on the new build everywhere I don’t remember.

GP specs say 1/2" bypass, but that could just be outlet size. Will look, because I remember being surprised.

Yea mine has the 1/2" bypass and outlet so thats what I started with… once I had it set properly it would surged every couple seconds and kick into bypass. Did a quick search here and read this thread and learned about the whole back pressure issue… ironically you were one of the posts saying to downsize to 1/4"… thats what I did and everything works as it should now.

That was with the 7

Regardless, I was having the same issues with the zk1 as the op in that thread and sizing down fixed it so all good.

OK, checked and both of mine are 5/8" hose and there is a sticker on newest one saying to use that, put by BCE. Both are 8.5gpm.

I have a large job tomorrow about an hour away, would it be prudent for me to wait on setting up this new unloader in case something doesn’t work right?

Yeah, play it safe. I hate being on a job and issues start popping up with equipment. You’ve made it this long, another few days won’t hurt.

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I added quick connects to my whip lines and unloader so everything is cake to swap out. 1/2 inch bypass works great at 6.8gpm.

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Thanks, figured as much. Anyone seeing issues with the K1 and Dez’s injector?

The correct model names are ZK1, ZK5 etc. It’s often abbreviated to K1, K5 etc. The 3/8 ZK1 is model ZK138

Not a peep on my end. You can be the first :rofl:

I’m not saying you’re wrong… but Interpump the maker of the unloader calls it the K1. Stateside GP brands them as the ZK1… but if you look at the embossing on any of them, regardless of what it was called from the seller when you bought it, it says “Interpump made in Italy” (mine even has a sticker that says “K1” on it) but yes, they are both the same apart from the option for 1/2" or 3/8" outlet which is available in either naming. Are the two companies tied together, GP a subsidiary of Interpump Group? Would make sense, but they are branded and marketed to different regions under different names. Which is where a lot of the confusion comes in when trying to figure out which one to buy and why.