What do single sealing and double sealing mean?
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The industrial pump selection manual contains a description of mechanical seals as shown in the figure; here, the terms single seal and double seal do not refer to single-face and double-face seals, right? Single layer or double layer?
A single-end face type has one set of moving and stationary rings, as well as one sealing surface. Double-end face means there are two sets of mating stationary and rotating ring surfaces, that is, a double-end face
This is the layout diagram for single and double configurations
In other words, does \"single seal\" here mean \"single-face seal\"? So does that mean that for environmental reasons, double-end seals are used in most cases?
Yes, with a single end face, the process medium leakage can be kept below 1000 ppm; for systems without pressure, such as 11+52, it can reach 500 ppm. Those under pressure, such as 53A, can achieve 0
The moderator is correct – there is a difference between double-end and single-end mechanical seals, that is, between those with two friction pairs and those with one friction pair
What’s the difference between back-to-back and face-to-face? They look the same
The toroidal directions with compensation are different; the back-to-back springs (for compensation) are in the middle, while the toroids are on either side, facing away from each other. Face-to-face springs on both sides, with a torus in the middle; the tori are opposite to each other.
Are the face-to-face dual-end compensation rings located in the static ring holder? They appear darker in color in the diagram; are these two face-to-face rings the static rings?
A face seal that typically consists of a pair of sealed end faces is known as a single-face seal, while one that consists of two pairs of sealed end faces is known as a double-face seal. Generally, single-face seal structures are relatively simple; they are also easy to manufacture and install. They are commonly used when the medium has good lubricity and minor leakage is acceptable. However, they are not suitable for use when the medium is toxic, flammable, or explosive, or when strict requirements are placed on the amount of leakage allowed. However, double-end face seals all have a sealing function of both axial double-end face sealing and radial double-end face sealing. Thus, some double-end face sealing structures arranged radially are more compact in operation than axial double-end face seals. Double-end face seals are generally suitable for situations where the medium in question has poor lubricity, is toxic, is flammable, explosive, or volatile, and may also contain abrasive particles or gases