Let's Talk About Threads

Let's Talk About Threads

We get so many questions about threads; it seems funny that something so simple (from the looks of it) gets so much attention, but it does. So, to clear things up, maybe it is time to talk about those seemingly "simple" threads and add a little more info about the Vecto.

When talking about threads, we mean the screw-like lips on the neck of the container (in our case, the Vecto) that connects with a cap or a filter for a perfect seal to prevent leaking. To take the Wikipedia definition (for a screw cap): "A screw closure is a mechanical device which is screwed on and off of a "finish" on a container. Either continuous threads or lugs are used. It must be engineered to be cost-effective, to provide an effective seal (and barrier), to be compatible with the contents, to be easily opened by the consumer, often to be reclosable, and to comply with the product, package, and environmental laws and regulations. "

Despite this apparently simple definition, things are not that simple: bottle threads are not standardized but follow more of a recommended guideline. Not only are they not standardized, threads for 28mm threads can fall under the set 28mm group (Alcoa, Orbist or PCO) or under the size ranges (SP400/410/415). 

To give a quick explanation, here are the main groups:

SP Threads

SP threads are recommended threads for PET (Polyethylene terephthalate) bottles in a variety of neck sizes, are meant to allow for easy closure, and have similar dimensions. In this group, there are SP400, SP410 and SP415. These are the most common threads, which have interchangeable caps that really only differ in the length of the neck (aka, depth of the cap).

In this group are also SP425 and SP430, which have a slightly different thread pattern and are usually used for a higher seal item.

The illustration below explains these threads:

Dedicated 28mm Threads

This group of threads was developed specifically for what we know today as soda bottles. There three main groups: two by Husky that are either for flat water (Obrist) or pressure top (Alcoa), and one by ISBT (International Society of Beverage Technologists). The ISBT threads are the most common so I'll only explain those:

The ISBT threads are used very widely for any pressure threads since they have a non-continuous thread (they have grooves) that are offset to allow an excellent seal.

The ISBT threads differ in where the point of connection to the bottle is (depending on bottle shape) and ranges from 1810 to 1823 and 1881, each with a slightly different thread shape. Many of the pressurize soda bottle use this thread as it provides an excellent seal.

To give you a better idea and perhaps offer some confusion, here is what a thread spec sheet looks like:

Now, Back to the Vecto

All this boring technical stuff has a point - we wanted the Vecto to work well with as many threads as possible. Despite the "28mm neck" claims of so many filters, in reality, they often end up having different threads. Even more frustrating, the thread can sometimes be different for each product. To solve that, we opted for a hybrid of threads to provide the most options for you when in the field: The Vecto uses thread shape from the ISBT PCO 1823 and fits them on the PCO 1817. This allows it to use the pressure seal of the PCO while working with SP threads (that are thin) like the PCO 1823.

Just to give some context, here are some of the threads out there:

  • Cola bottle: PCO 1881
  • Old Cola bottle: PCO 1810
  • SmartWater bottle: PCO 1817
  • Sawyer collapsible bottle: SP 415
  • Platypus bottles: SP 400 (old), SP 410 (new)
  • Evernew bottles: SP 415
  • Sawyer mini filter: SP 410
  • Sawyer Squeeze filter: SP 415
  • HydroBlu Versa Flow: SP 425

The above makes you wonder, why do the SmartWater bottles work so well with the Sawyer filters but not the HydroBlu? Simple: the PCO 1817 has thicker threads that won't fit well into the HydroBlu's thinner grooves. This is why we used the thinner threads of the PCO 1881 on the 1817 shape, so they both fit!

We hope that wasn't too confusing to you and if you really want to dig in dipper into the world of threads and tolerances, here are two more resources:

ISBT Thread spec

Standard Specification for Dimensions and Tolerances for Plastic Bottles

Last Note About Threads and Vectos

The one thing we have heard the most from you is that you find the Vecto's threads to be too soft to get a good seal with some filters, mainly the Sawyer Mini. The reason for this problem is that the Mini has the oddest thread of them all (it works well with old soda bottles) but works great with everything else. To solve this, we are increasing the density of materials on the neck so you can use more torque to seal the Mini on properly.


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