Mechanical seals Tandem

Figure 11.3 Double mechanical seal, tandem configuration (Courtesy of New Brunswick...

Use double or tandem mechanical seal with inert seal fluid... 

Figure 3-31B. Typical seal flush arrangement for tandem mechanical seals.

Maximum Allowable Working Pressure, code, 399, 405, 406, 408 Mechanical seals, 171-177 Fundamentals, 172 Inside, 172 Installations, 173 Lubrication, 174 Outside, 173 Seal flush system, 176 Tandem, 177... 

The standard unpressurized dual mechaiucal seal (previously referred to as a tandem mechanical seal) shall be a balanced seal (with two flexible elements and two mating rings in series). Unpressurized dual mechanical seals shall be designed to withstand pressurization of the bnffer flnid to 275 kPa (40 psig). 

Tandem mechanical seals, lubricated and blocked by a seal gas with slightly higher pressure than the gas discharged by the compressor offer major advantages. There is no contami... 

Semi-hermetic tandem pumps are also used for supercritical gases, in the same way as tandem pumps are used for high system and discharge pressures as described in Section 5.3. In order to separate the liquid-filled rotor compartment from the gas zone, the pump is fitted with two mechanical seals. Accordingly, fluid can no longer be fed from pump 1 to pump 2... 

Fig. 12. Arrangements of mechanical seals. Double seal higher pressure fluid between seals creates an artificial environment for seal operation. Tandem seal two single seals with a buffer zone in between them. One backs up the other.

Plant updates tandem mechanical seals, leak H H... 

Tandem mechanicai seai combines benefits of singie and doubie mechanicai seais (singie mechanical seal with flush also available)... 

There are three types of mechanical seals ng e, double, and landcm. The double mechanical seal has two mechanical seals mounted back to back. The tandem mechanical seal consists two mechanical seals mounted in series. Double and tandem mechanical seals arc more effective than the single mechanical seal. 

The dry gas seal is a variation of the mechanical contact seal. It differs in that it uses a microscopically thin layer of gas to separate and lubricate the faces. The seal is configured in a tandem or double-opposed seal arrangement. More complete details are covered in Chapter 5 under Dry Gas Seals. 

A disadvantage of tandem seals is that they cannot safely be operated without process fluid because the seal on the process fluid side may run dry. Also, the springs and other internal seal mechanisms on the fluid side run in the process fluid, which may not be good in highly corrosive fluid. The big advantage of tandem seals is that they allow process fluid to be pumped without contamination from lubricating oil, and the chances for major loss of process fluid are small. 

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