Dear Lab Guy,
I was looking at the SP Bel-Art Reagent/Acid Pump Dispenser and found it lists the compatible bottle interfaces as GPS No. 38-430 or 38-400. I'm not familiar with these labels and I'm hoping to use it on a GL45 compatible bottle. Will this work for me?
Hi Marshall,
Cap sizes and neck finishes are expressed as two numbers. The first number indicates the diameter. For caps, this number represents the inside diameter of the cap. For the neck finish, this number represents the outside diameter of the threads on the neck of the bottle.
As can be seen in the example to the left, the dashed red line indicates the inside diameter of the cap as well as the outside diameter of the threads on the neck of the bottle. In this example, the number for both is 28.
The second number refers to the thread style. The most common thread styles are shown in the image below. Each style is designated by a number. The differences among threads styles are the number of thread turns and height of the neck finish.
Going back to our example cap and bottle neck shown above, the threads make one and a half thread turns around the bottle. Comparing this with the common thread styles image indicates that the thread style is a 410. So the second number for our example is 410. We now have all we need to determine both the cap size and the neck finish for our example. The diameter is 28mm and the thread style is a 410, so the cap size and neck finish for our example is 28-410.
As for your GL45, GL stands for “German Bottle Closure Thread Series”, and it is 45mm in diameter. It looks like the 430 Buttress finish shown above. The Reagent/Acid Pump Dispenser will fit on top!
I hope this helped and answered your question. Thanks for writing in, and please feel free to write back if I can help in any other way.
Yours in science, Lab Guy
