Once again, I'm sure glad you are building your system and have been asking some questions that I didn't ask myself when I designed this in the first place.
The 250 psi label on your carbonator pump is the max relief pressure. Mine is labled with that too. However, the max pressure of the pump itself might be less. The pump on my carb motor is a Procon 141A100F11AA and the specs for it say it has a 200 psi relief valve and is 150 psi at 1/3 hp. Even the good braided beverage tubing has 200 psi rating at 70 degrees but only 100 psi at 100 degrees.
Since this is in my garage and I live in Texas, it gets warm in there in the summer. I think 150 psi will be over the limit of this hose in summer temperatures. I'm lucky my hose hasn't failed. Thanks to you, I've caught this.
I am thinking at this point I will change to a solid stainless tubing for the line from the carb pump to the carb tank.
I'm looking here to get an 8ft or so long piece of stainless tubing:
I've purchased from this company before.