Myron, here's my interpretation of your photo:
- the "fits on 20 pounder" is a POL (a.k.a. CGA 510) fitting, attached to a regulator, which I assume is the trailer hose to which you want to supply propane
- the "fits on Coleman bottle" end is a needle valve fitting to receive propane, presumably on the end of the hose you bought
- the "fits on ?" fitting is the mating needle valve fitting to supply propane; it is just like the fitting on the top of a disposable propane cylinder ("little Coleman bottle"), and would normally include a valve (tripped open by inserting the needle of the mating fitting); presumably this is on the other end of the same hose
- the hose you bought is a needle valve extension, which does not serve as a converter between types of connection.
The adapter which is required has a needle valve fitting to receive propane from the disposable bottle on one end, and a POL fitting like a bulk (e.g. 20-pound) tank on the other end. I use a needle valve extension to connect my Boler
tanks to my barbecue, and I have an adapter like this at the end to make the needle valve hose work with barbecue, which I believe is basically what Myron needs.
This type of adapter is sometimes sold as a "steak saver", because it lets you finish barbecuing that last steak when the propane runs out, by using a disposable cylinder. Other names include "second chance propane grill adapter" or "reserve gas adapter". I found mine at a specialty barbecue store (Barbecue Country
), which has a wide range of adapters and hoses. I would certainly go back there - rather than the overpriced and under-stocked RV parts store - for any future propane fitting needs, but for reference here there is one listed at Camping World as "Propane Grill Steak Saver Adapter
<blockquote>Note: Myron's trailer has the old POL fitting, like mine. More recent bulk tank connections use the current QCC connection, and the newer tanks I have accommodate either type (the threads are different, but the bullet-shaped gas connection is the same). Some of the adapters which I have seen are specific to one of the two (POL or QCC) - although that one at Camping World says it works with both - so I would check to be sure. Coast has models of each connection type on page 44 of their current (2006) catalog (Barbecue Grills and Accessories
), from Marshall, which seems to be a common manufacturer - most of my hardware is Marshall.</blockquote>
So the right adapter has a needle valve fitting with female threads and a protruding needle on one end (to fit the cylinder) and a POL (or dual POL/QCC) fitting with female POL threads (and maybe male Acme threads for QCC) and a socket to receive the trailer hose's bullet-nosed fitting on the other end.