Dating vintage equipment is always a challenge. Even the patent dates on some of the equipment will only tell you the patent date even if it was made and sold 10 to 20 years down the road. Making molds has always been an expensive time consuming task. Today with CAD design and rapid prototyping, industry can cut many development costs and time but years ago it was all hand work in most cases.
Probably the best way is to collect all of the Sears, Wards and other catalogs you can which will give a good idea of what was being produced when. Most of the catalogs I have seen covered the rubber goods pages in black and white saving color for the high end clothing and home decoration pages. They would however describe the colors of the equipment in most cases. As time went on, the 4 quart bags seemed to vanish by the early 1940's. Three quart bags could still be found into the early 1950's but they too began to vanish with the introduction of the extra capacity over two quart syringe bags in the top end equipment. It was amazing what could be found in the plain brown Kraft paper wrapped catalogs of years gone by.
The clamps have always varied according to cost. The more expensive equipment always seemed to be equipped with the very elegant lever style clamps while the less expensive units came with the generic snap type clamp which by design was cheaper to make. The use of threads to hold the nozzles into the hose end was also a more expensive way to make equipment. A straight threaded nozzle with a thin rubber gasket was always going to stay sealed. The slip on style fittings became more popular in later years as they are much cheaper to make.
The nozzles went from the nice black hard rubber or Bakelite to the grey or white plastic of today. Some outfits were equipped with up to 4 nozzles and today two nozzles seem to be standard.
It is clear to see that during the Golden Age of enemas, douches and syringes, that some of the most elegant equipment was offered with often several catalog pages devoted to rubber goods. Over the years, those several pages shrank to often times only one page and by the 1970's, perhaps only a part of a page being shared with other sickroom supplies as it was called. The good ole days are gone and the memories are priceless. The 1941 Wards Fall-Winter catalog has an incredible display of syringes over several pages with very detailed descriptions. This was right before WWII when the economy had recovered and advertising was on the way up again. The catalogs were being printed bigger than during the depression years and to see one from the early 1940's is a wonderful trip down memory lane never to be repeated.
Years ago I collected old catalogs in antique shops when I could still find them at reasonable prices. Often times they were only 5-10 dollars a copy for one in good to excellent condition. I lost some of them in a nasty divorce but most of them survived and they are stored away in boxes. Perhaps it is time to shoot some photos of what used to be commonplace in our lives.