Tubing types vary from country to country. To make matters worse, we don't use the metric system here in the U.S. (what's wrong with us?). Once the unit of measure has been sorted out, most everything else comes down to the type of plastic used to make the tubing.
Once you know your plastic type (described below), the Inside Diameter and Outside Diameter are the next specs that are useful to know. These dimensions determine your tubing wall thickness, which is a factor in how heavy your tubing/hoop is. If you're a plumber, it is a factor in how much pressure (p.s.i.) you can run through the tubing. Similarly, your hoop itself has an ID and an OD (we measure our hoops by OD).
What is sometimes confusing is that some folks denote a tubing size by its ID while others label it by its OD Here at Synergy, we often disclose both measurements since standards vary from industry to industry although we've found the hoop industry defaults to OD. When choosing the correct size Quick Wick ® you'll need to know the ODof your tubing.
Common Types of Tubings (U.S.)
PE is the plastic used to make "the classic black tubing" found at Lowes & other hardware stores. Some people get it from different places, but no matter where it comes from, it seems to be the most easily obtained tubing around (as it is commonly used for irrigation) for making good Beginner Hoops. We do not offer black PE firehoops, but do have Quick Wicks® that can be used with PE hoops. NOTE: this tubing most always has it's Inside Diameter printed on the tubing, which is not actually its true ID (sort of like how a two-by-four is not actually two by four inches)...
3/4" 100psi : True ID is about .82" and the OD is about .95". Use 1" OD Quick Wicks.
3/4" 160psi : True ID is about .82" and OD is about 1.1". Because of this heavier weight (thicker tubing walls), 160psi hoops are not recommended for Quick Wicks although the 1" OD Quick Wicks will fit on this tubing.
1/2" 125psi : True ID is almost exactly 5/8". The OD is approximately 3/4".
High-Density Polyethylene (HDPE)
This type of tubing is not commonly found in hardware stores, meaning the funny two-by-four rule does not apply. If you get 3/4" OD, it will have an actual outside diameter of 3/4". We offer three sizes for our hoops & firehoops:
1/2" ID, 5/8" OD HDPE (Thinnest, good for hoops 32" and smaller)
5/8" ID, 3/4" OD HDPE
3/4" ID, 7/8" OD HDPE (Thickest, good for hoops 36" and bigger)
If you use 3/4" 100psi black PE tubing for your regular hoops, 7/8" OD HDPE would be a great tubing for your firehoop, as the added weight of the wicks will balance the lighter weight of the tubing. Similarly, 3/4" OD HDPE will be similar to 1/2" PE but a little lighter. If you want a large hoop (38"-42" hoop size), the wider/thicker 7/8" OD will work better because bigger tubing is stronger for larger hoops.
"Polypro" has become many hooper's favorite tubing because it is super light and very rigid, offering a quick, tight & easeful response. We offer two sizes for hoops & firehoops:
5/8" ID, 3/4" OD
1/2" ID, 5/8" OD
Natural (un-colored) PP is a translucent & semi-clear tubing, but we offer an awesome variety of awesome colors for both regular polypro hoops and polypro firehoops. PP firehoop sizes greater than around 36" become more flimsy so if you want a larger firehoop, you may want a thicker/wider tubing like the 3/4" ID, 7/8" OD HDPE.
Polypro Geekery: There are two main types of polypropylene tubing. "Homopolymer" polypro tubing is the more rigid variety and has been known to crack instead of kink especially when very cold, while "random co-polymer" polypro tubing is slightly less rigid than homopolymer. Because co-polymer polypro is more flexible, it will usually kink before it cracks. We have invested way too much time & money into research of polypropylene, but that's what keeps us innovative. Once upon a time we commissioned a custom-blended batch of PP using 50% homopolyer / 50% copolymer. It reacted much like homopolymer and was found to be susceptible to cracking. Once having used homopolymer for our hoops & firehoops, and then the 50/50 blend, we have now decided that co-polymer PP is the best for hoops & firehoops because of its resistance to cracking.