Complete disassembly-Class A and Class B cavities

Many of the descriptions in the standard are rather obscure. Of course it is understandable to a certain extent, after all, accuracy is needed. But of all the difficult descriptions, the high level of complexity in the descriptions of Class A and Class B cavities definitely ranks in the top three. What is Class A and what is Class B? Are all cavity structures encapsulated in Class A and B?

The definitions of Class A and Class B cavity loads are written in the Chinese standard for small sterilizers, YY 0646-2008, which is a translation of the European standard for small sterilizers, EN 13060: 2004. So the predecessor of the definition of Class A and Class B cavities are from the European standard.

First of all, let's make a brief summary. First of all, let's make a simple generalization.


We can simply understand: Class A cavities are narrow and long, Class B cavities are short and fat.
Generally speaking, class A cavities are more difficult than class B ones.
Class A and B cavities are only two ranges listed in one standard and do not include all lumen types.


Now let's have fun reading the definitions of Class A vs. Class B in the standard!

    Class A Cavity Load Hollow Load A single-ended open hole load, the length (L) and hole diameter (D) ratio is greater than or equal to 1, less than or equal to 750 (1 ≤ L / D ≤ 750) and the length of the line is not greater than 1500mm (L ≤ 1500mm), or both ends of the open hole load length and hole diameter ratio is greater than or equal to 2, less than or equal to 1500 between the two ends of the open hole load (2 ≤ L/D ≤ 1500) and length is not greater than 3000mm (L ≤ 3000mm), and does not belong to the class B cavity load. (2≤L/D≤1500) and the length is not greater than 3000mm (L≤3000mm), and does not belong to the class B cavity load.


Class B cavity load Hollow Load B single-ended open hole load, its length (L) and hole diameter (D) ratio is greater than or equal to 1, less than or equal to 5 (1 ≤ L / D ≤ 5) and the hole diameter is not less than 5mm (D ≥ 5mm), or both ends of the open hole load and the length of the hole diameter of the ratio is greater than or equal to 2, is less than or equal to 10 (2 ≤ L / D ≤ 10) and the hole diameter is not less than 5mm (D ≥ 5mm). D≥5mm).

If this is the first time you see it, I believe you and we feel the same way. Every word here is recognizable, but when combined together ...... is this a tongue twister in the disinfection world?

Well, disassembly time is here again! Let's take the above description step by step and deconstruct it again.

First of all, the definition of class A and class B both have this sentence: single-ended open hole load, its length (L) and hole diameter (D) ratio is greater than or equal to 1. Single-ended open hole is a blind-ended lumen, so let's first draw a cross-section of a blind-ended lumen, whose length to inner diameter ratio is equal to 1 (below, left).
In the case of a single-ended blind-ended lumen with a length-to-diameter ratio equal to 1, the length and diameter are equal (above left). If the ratio is less than 1, the lumen length is shorter than the inside diameter, which is not part of the standard definition of a lumen (above right). Since the ratio needs to be greater than or equal to 1, this means that the length of the tube could be a little longer. But it can't be infinitely long, so here's where the difference between Class A and Class B comes in.
Class A


The requirement for the length of the blind end lumen of Class A is that the lower limit of the ratio of length to diameter is 1 and the upper limit is 750, so if the diameter of the lumen at the blind end is 1mm, the upper limit of the length of the lumen is 750mm.

At the same time, the upper limit of the length of the blind end of class A is 1500mm, which means that the length of class A cannot be unlimited.

The first half of the definition of class A cavity is the ratio of the blind end of the lumen, and the second half is the double-opening lumen. Teachers who have read our previous tweets (single opening vs double opening links) will know that a double opening cavity is equivalent in penetration characteristics to a blind end cavity that is only half its length. So the ratio of length to diameter becomes 2 for the lower limit and 1500 for the upper limit, so if the diameter of the double-open lumen is 1mm, the upper limit of its length is 1500mm, and the upper limit of its length is also doubled to 3000mm.

The last sentence of the definition of a Class A cavity is that it is not a Class B cavity. So what are the requirements for a Class B cavity?
Class B


Class B cavity on the blind end of the length of the cavity requirements: length, diameter ratio of the lower limit is 1, the upper limit is 5, and on the hole diameter has strict requirements: not less than 5mm. so in fact, class B cavity is a relatively short and fat cavity. Assuming that the diameter of the blind end of the cavity is 5mm, the upper limit of its length is 25mm.

Similarly, the definition of double-open pipe cavity is doubled. That is, the length of double-open B class cavity, diameter ratio of the lower limit is 2, the upper limit is 10.

Because there is a specific requirement that the inner diameter of a Class B cavity must be greater than or equal to 5mm, this means that the inner diameters of all Class B cavities are larger and the lengths are not allowed to be too long, up to 5 times the inner diameter. Therefore, the difficulty of short and fat Type B cavities is generally lower than that of Type A cavities.

SUMMARY


Let's make a summary!


In general, we can simply understand that Class A cavities are narrow and long, and Class B cavities are short and fat.
Class A and B cavities are only two ranges listed in one standard and do not include all lumen types.
With a fixed I.D., the maximum length of a Class A cavity at the blind end is 750 times the I.D., and the maximum length of a Class B cavity at the blind end is 5 times.
Class A is not infinitely long. In the case of blind ends, the maximum length is 1500 mm.
Class A does not specify a range of internal diameters; Class B specifies that the internal diameter must be greater than 5mm, but gives no upper limit.
If you go from a blind end to a double opening, all limits are doubled.