Sealant for Potable Water

1. Make/model# of pump?

2. Can the fittings be changed out for barbed fittings?

3. You really need to know what materials of construction are in this pump.

4. How was it done at the factory?

5. Not crazy about using cyanoacrylates, unless the are medical grade.

6. Maybe a silicone?

The fittings are cast into the pump body and cannot be changed.

I am pretty sure the pump is ABS

Very little silicone meets potable water standards. Those that do are not available is small quantities or locally.

The pump manufacturer says to use a clamp and smaller tubing and force it on. They said the pump material is a type of nylon, but food grade. They advised no sealant but said it must be food grade if I chose to use one. I was lucky to make a contact that could type English, although it was obviously not his first language. I will try to find a tube that is less than 1/4 but greater than 3/16 which will not fit. 5 or 6mm would probably work if I can find it.

I would give these guys a call....

http://www.masterbond.com/properties/food-safe-adhesives-sealants-coatings-encapsulation-compounds

I have had problems in similar applications. I find on many its not the pressure or the clamping force. It's the seam on the fitting where the die halves were off set or a crack in the fitting. I would replace the fitting not the hose. Find a good compression fitting for plastic hose.

What about either scraping or filing the mold flashing off the fitting so it didn't leak due to this. I have used this numerous times to get tight fits on plastic fittings.

Also consider filing a small shallow notch all around the fitting near the hose end to give the tubing and clamp something to "hold onto". This would be similar to the fittings used for polyethylene plastic tubing for lawn sprinklers and wells but with far fewer barbs.

Also consider using reinforced vinyl tubing instead. The woven reinforcing will give it much more strength and higher temperature tolerance.

I have used these tactics at one time or another and they worked. Sometimes for an emergency and sometimes for permanent installations. Most of the emergencies installs ended up being permanent due to forgetfulness or laziness.

Good Luck, Old Salt

You could make things much easier for the forum if you'd publish your location.

It can be added to your profile.

If this is for hot water, you are likely not drinking it, so why the food grade requirement?

Have you considered reforming the end of the fitting with a bit of heat to get a barb type arrangement on it?

Can you build up the outside surface of the fitting with a suitable epoxy that will adhere to the fitting, form a barb type shape into this epoxy, and then fit a suitably upsized tube?

The water will be at the kitchen tap for the hot water. There is not enough room between the inlet and outlet of the pump to add a barb. I tried 3/16 tubing and it appears to work if I can also get it over the barbed 1/4 fitting at the other end of the tube. I am going to try to clamp with a double wrap tie wrap the way a lot of newer Japanese car are doing nowdays. I've tried it on radiator hoses and had success, but they only get to 15psi or so. This pump develops about 28 psi. Ironically it doesn't seem to leak anymore at pressure than just sitting with no pressure. For those who have thought a problem might be a flash or casting mark at the fitting, that is not the case, the fitting is smooth. With the small diameter, I have had no problem with the tube coming off, it just slightly seeps is all. I was able to get a seal with the 3/16 tube that didn't leak. I did find out that the local hardware can get a sealant that is food grade without costing me shipping. If I need it, I will order that, but right now I think I can get a seal without it.

It does seem a little odd to be boosting the hot water for a kitchen sink and then using only 3/16in tubing to get it there, however, noted that this is for a camper connection..

• For a fixed installation one might use a single- or double-impeller mains-operated shower pump with a decent-sized connection for the tap/faucet. If the unit were installed in the UK, 15mm copper pipe would be one of the many ways of getting there, and most shower pumps have a BSP screwed fitting that accepts a flexible hose connector with a push-fit connection on the other end for the copper pipe. http://www.screwfix.com/c/bathrooms-kitchens/shower-pumps/cat820270 (usual disclaimer).

A silicone sealant for fish tanks is safe,reasonably priced and available at most pet shops in small tubes. I have used this on the plumbing in my RV with success.

Our town has no pet shops. Thank you for the tip, I will keep it in mind.