I while back I fitted at vacuum toilet and brought what I thought was the correct (best) sanitary hose. Well, it was made of the right material, but the inside of it had a raised spiral ridge just like the outside. I used a hot air blowers to soften the hose before applying double hose clamps (pre-greased) everywhere.
The vacuum pump was able to pull a vacuum, but it always leaked and the vacuum pump would cycle about every 15minutes. Over the years I continued to nip up the hose clamps but the leaking problem never really improved.
Recently I saw that Road Tech Marine had a similar sanitary hose to what I had used, but the internal ridges was very minimal. So I bit the bullet, brought some of the hose and fitted it (hot air and double hose clamps) and no more leaks.
Leaks = No juice ever came out, but air was entering the chamber,
Another Learning$$ curve. Maybe everyone one was aware of this issue with the different sanitary hose internal ribbing heights, but hopefully someone may benefit from my experience. 
Hoses definitely ain't hoses!!!
I work for a large Tassie hose supplier and we supply an Italian made sanitary hose. The chinese stuff some of the big chandleries stock is exactly as you said and also causes weak spots and the hoses cam crack after less than a year.
I have had two customers who put the 19mm on their toilet inlets only to have to fail. Fortunately they were on the boat at the time and they were able to shut the seacock off before the boat sunk!!
Bit of a wonder why a so-called sanitary hose would have a ribbed interior surface, providing places for stuff to adhere.
On the subject of hoses, often one sees anti siphon loops on suction hoses for marine heads and engines. To my mind this defeats the purpose as the bleeder valve will allow air to be drawn into the line.
Any thoughts on that???
Select to expand quotecisco said..
On the subject of hoses, often one sees anti siphon loops on suction hoses for marine heads and engines. To my mind this defeats the purpose as the bleeder valve will allow air to be drawn into the line.
Any thoughts on that???
Exactly Cisco, an anti siphon valve before a pump?? The only way the pump could work is that the amount of air drawn in through the vented loop must be negligible. A decent amount of lift required from the pump and efficiency losses from having a vented loop would surely be there, all the way to pump failure. I cannot see any good reason for having one before a pump and I'm sure often you see them fitted because of a lack of understanding.
With regards to the anti siphon loop on the suction line to the head. Again, the pump still works because the amount of air in drawn into the line is negligible. May be some don't trust the valve in the pump out head. I know I don't, so I keep the seacock closed,,, or maybe the seacock for the head is shared with other applications so the seacock is required to be left open. Which ever the case, if the lift is low and the pump still works, having an anti siphon device may be a wise choice.
Select to expand quote
"The extra suction generated by Jabsco electric toilets will open the valve in vented loops, drawing in air and preventing priming. The Solenoid Valve attaches directly to Jabsco Vented Loops and is wired to the toilets on/off switch."
Thanks Lazzarae, the electric solenoid on the loop makes good sense. 
