Actual Sanitation Hose ID/OD? Bonus Rant at End

[BrightSEALAB]

Need to replace waste tank vent line.

It's a shields something-or-other series 148 with an actual OD of 1". I would like to be certain of the nominal hose size before I buy the replacement and I would prefer to not pull the system apart in order to measure the hoses actual ID. I would rather have the appropriate replacement hose on hand when I pull the old one off.

I'm usually pretty good at ferreting this information but I'm stumped. I actually found a Shields product brochure here that gives all the info someone might want except the actual dimensions of their product.


The following is a much larger rant than originally planned...

Is this normal? In any other industry this information would be the first set of results of a google search. What's the actual OD of 1/2" copper pipe? 3/4" PEX, 2" schedule 40 PVC? All brilliantly easy to find answers; 0.625", 0.875", and 2.375" respectively. Quarter-inch vinyl tubing? It has an OD of 1/4" and an ID of 11/64". I was able to get these numbers in real-time as I typed this by asking Alexa.

When I googled "Shields series 148 actual OD", the first few pages were all distributors of the hose (none included this information) and none were from the actual manufacturer. The brochure I found does list the manufacturer as Teleflex Marine with a website. But that website is a dead link because the company changed its name and doesn't feel like paying the $10 a year to maintain their old URL. This is a huge middle finger to their customers.

Then, when I find their current website, complete with a comprehensive catalog, it STILL doesn't provide complete specifications for the product! Like the brochure, they list nominal diameter, actual ID, and that's it. They could have listed actual OD or they could have provided "Wall", either would give me what I need and in every other industry where people buy tubing or pipes it is common practice to do so.

I would give Shields / SeaStar Solutions / Dometic a thumbs-down but I suspect everyone else making marine hoses does the same.

Okay... a ketamine dart just hit my neck, the wife must sense my agitation...

[peghall]

Because hose OD can vary with the wall thickness of the hose, all nominal hose sizes use the ID...and the standard vent line is 5/8" ID. Hose FITTINGS use OD to match the ID of the hoses that go onto 'em.


Btw, Shields or Trident #148 is what you're looking for.


--Peggie

[BrightSEALAB]

Originally Posted by peghall

Because hose OD can vary with the wall thickness of the hose, all nominal hose sizes use the ID...and the standard vent line is 5/8" ID. Hose FITTINGS use OD to match the ID of the hoses that go onto 'em.

--Peggie

You're not suggesting that the wall thickness of, say, a Shields 148 1" hose varies significantly from one batch to the next?

Actually I would wager that the OD of the most common 1” marine sanitation hoses are close enough that knowing that by knowing that OD one could be fairly certain of a hoses nominal size.

And this would be handy for me because I cannot measure the hose I have's ID without taking it off the fittings to which it is attached. An act that will certainly render this hose incapable of being reattached.

I can guess that this vent hose is the common 5/8”, but it's not a sure bet from my perspective as the previous owner made all sorts of departures from the norm. Is the wall thickness of 5/8" sanitation hose 3/16"? Maybe. That seems a bit much but I've never worked with the stuff so I can't say.

I have a hard time believing this isn't an industry being intentionally abstruse. If I found a fragment of household plumbing pipe or tubing, knowing nearly any non-nominal dimension, 8 seconds on Google would give me the nominal size needed to buy its replacement.

I know the marine hose manufacturers know the wall thickness and OD of their products. They choose not to publish it. Contrast with your basic schedule 40 PVC pipe by Charlotte Pipe (or any brand) where every place that sells it lists its nominal size, it's actual ID (if different), as well as wall thickness and actual OD. Charlotte Pipe actually provides a dimensional catalog with all their product dimensions to download. Same goes for copper and PEX, pipe. Same for vinyl and PET tubing.

On the few occasions where I find a hose that's dimensions are not easily discovered online, radiator hose for example, an extra few seconds of looking and I discover the information I need written on the hose itself. Information Shield could have put on the side of this hose after the text indicating its manufacturer and series number. Why wouldn't the company put the hose size on the hose?

[peghall]

You're not suggesting that the wall thickness of, say, a Shields 148 1" hose varies significantly from one batch to the next?

Of course not. But #148 flex PVC isn't the only hose used as holding tank vent line.

And because all hoses have to be a match for the fittings they go onto, all MARINE hose nominal sizes are stated according to their IDs. People can run into problems when they try to use domestic or automotive fittings instead of marine fittings because domestic thread/barb fittings can be (example) 1.5" OD threaded x 1.5" ID barbed.

Shield could have put on the side of this hose after the text indicating its manufacturer and series number. Why wouldn't the company put the hose size on the hose?

I'll let Shields answer that question.


--Peggie

[waterman46]

It's always been a frustration with plumbing that they can display all sorts of lot numbers, trademarks, etc. onto the fittings and hoses but somehow they can't find room for the nominal sizes.

No doubt the OP has a "3/4 inch" hose, but why can't he disconnect the upper end of the vent hose and try to insert a known size nipple into it to check?

[peghall]

why can't he disconnect the upper end of the vent hose and try to insert a known size nipple into it to check?

He said he doesn't want to remove any hoses until he has new hose in hand to an immediate swap out. It can be hard to help some people.


--Peggie

[BrightSEALAB]

At the risk of sounding pedantic... I'm really not, just... up to my elbows in yech on a much too stinky boat and frustrated by an industry practice that has added days to this repair for no reason.

Originally Posted by peghall

And because all hoses have to be a match for the fittings they go onto, all MARINE hose nominal sizes are stated according to their IDs.

I don't have any problem with a hose being sized by its ID. That's commonplace. Even pipe that is segregated based on the OD gets its nominal size from the ID of early prototype iron pipe.

But with most pipes, tubes, and hose that you meet in the wild, finding out it's nominal size, and thereby purchasing a replacement is fairly easy. It's either written on the thing somewhere or, by measuring some aspect of it, can be found easily in some manufacturer published reference.

Being able to positively identify a hose size on one's boat should not have to require measuring that hose's ID, because that would require shutting that system down. Maybe that would mean shutting it down long enough to remove the hose and measure and then reinstall the hose, or maybe as in my case that would mean shutting the system down until the replacement (which cannot be ordered without this information) arrives.

I say it should not because there is no reason that it must except that the manufacturer has decided to withhold this information. It's a practice I'm finding common in this particular industry and I'm not really sure why.

Originally Posted by peghall

Why wouldn't the company put the hose size on the hose?
I'll let Shields answer that question.

It isn't just Shields, and getting an answer from them would be interesting. Mainly because this is 100% a deliberate decision on their part. Shields publishes a catalog with all manner of hose information given for each product. They give the vac rating for each individual hose entry in this series even though they are all the same number. Yet they don't give the wall thickness or actual OD; either of which would let someone identify the nominal size of a hose they have on their boat or let someone determine if they have clearance for that hose through a bulkhead opening or whatever. That's information they have that they choose to withhold.

Of all things, this reminds me of the model train industry. The manufacturers are so beholden to their distributors that they intentionally make it difficult for customers to work with them directly. The distributors eek out provisions that keep the manufacturer from selling to customers directly and often carve out exclusive territory. To get a particular locomotive once I was required to request a printed order form by mail. I had to mail the request (and return postage), the order form arrived a couple weeks later, I filled it out (WITH A PEN) and mailed it to them (with a check), and 7 weeks later the locomotive arrived. It was the wrong color but at that point I just repainted it. This was in 2015 by the way.

Originally Posted by waterman46

No doubt the OP has a "3/4 inch" hose, but why can't he disconnect the upper end of the vent hose and try to insert a known size nipple into it to check?

Because the last time I pulled a hose off its barb in this boat the last 3 inches disintegrated and I had to do without one of our heads for 3 days.

The sanitation plumbing in this boat already breaths into the cabin enough as it is, I don't plan to pull anything apart until I have its replacement in hand ready to go.

It actually is 7/8" hose, good call that. I know because I called the guy at West Marine and asked him what the OD of 5/8" Shields 148 and he said 7/8" then told me that the 3/4" hose has an OD of 1". When I asked where he found that information (and that I wasn't doubting him) he said you can't without measuring it but people come in asking so often they measured it and had it written down.

So now I'm ordering my all my future hose from West Marine. They are overcharging me to a criminal degree but their customer service is incredible.

[mitiempo]

Od of hose is a meaningless number, Id is how hose is measured. Typically 5/8" for vent hose. But it could be larger. For instance my vent hose is 1" as my vent is a 1" through hull for better ventilation.

The best solution is to remove the hose from the upper end and measure the nipple it has to fit on.

All the hose we sell has the id written on the hose. I have never seen marine hose - sanitation, exhaust, water etc - without the id stated on the hose exterior.

Od is meaningless.

[BrightSEALAB]

Say you have a water hose, a part of the system you don't work on much.

You don't know the size of the hose barbs it's clamped to. You only know the maker and the series of the hose in question. And you can measure the hoses OD in place.

It doesn't label the nominal size (usually the hose ID) anywhere on the hose itself. How do you determine the nominal size of this hose without shutting that system down?

Much like the general anesthesia statistic they don't mention on your way to the OR, about 1% of us who get turned off never get turned back on.

Tearing down a fluid system because it's the only way to be sure you're
ordering the correct replacement part is simply a primitive approach. One that will surely pay out 99 times before leaving you dry (or wet... ir worse )

[mitiempo]

Od is meaningless. Measure the barb the hose fits on. You have to remove the hose to replace it anyway.

[oleman]

I have been fighting the hose and pipe industries peculiar measuring systems for the past 70 years. IMO it all dates back to clay pipe where the wall thickness would vary from section to section and they only speced out the ID or OD of the finished product.
The only flexible line I know of is JIC or AN, used in aviation and hydraulics and in some fuel lines that specs out ID and OD of their products. That line has precision fittings and uses the ID and OD in making a connection. Even in that system, the dimensions are a trade secret and a user purchases a hose based on some arbitrary number system for example AN6 or JIC6 BUT AN is actually a US Government spec for aircraft fittings so its characteristics are on file.

[Cheechako]

Most Shields hose has labeled size on the OD stripe. it may be embossed. Are you sure it's Shields?
Hose brands vary a lot as Peggy said. One brand may slip right off a fitting, another be near impossible to put on.
Most my boats had that clear vynil (?) reinforced hose for vents. It's more impervious to odor than Shields also. I find the small diameter, like 1" and less, Shields type hose difficult to clamp tight and keep from slipping off some fittings.