Pump sealing type

Different pumps have various sealing types, and the choice of seal is determined by the properties of the material being transported; these include mechanical seals and packing seals. You can search the forums; there’s a lot of information there.

The selection of mechanical seals takes into account factors such as the medium, pressure, temperature, rotational speed, and shaft diameter.

Technical parameters—Guide to selecting machines: Each mechanical seal can function effectively only when used within its specified range. Improper selection can significantly reduce the sealing performance, shorten the lifespan, and even lead to failure. The main parameters for selection are as follows: 1. Medium pressure P in the sealing chamber. When the medium has good lubricity but a high viscosity, choose a non-equilibrium type when P≤0.8MPa. When the lubricity of the medium is poor and the viscosity is low, P≥0.5Mpa. II. For linear velocity V where V≤25m/s, a rotary type should be used. The stationary type is selected when V≥25m/s. III. PV value The PV value is related to the stability (vaporization) of the fluid film between the sealing surfaces and the wear resistance of the friction pair. Examples of PV limit values: End face composite material, Medium, Unbalanced type, Balanced type – Cobalt-chromium-tungsten alloy/graphite, Water: 2, 7; Tungsten carbide/graphite, Water: 9, 35.5; Silicon carbide/graphite, Water: 35.5, 142; Silicon carbide/tungsten carbide, Water: 7, 26.6; Tungsten carbide/tungsten carbide, Water: 2, 9. IV. Temperature of the sealing medium T: In the absence of external cooling, the maximum temperature that a mechanical seal can withstand generally depends on the safe operating temperature of the auxiliary sealing material. See the table below: Material, Safe operating temperature in °C, Remarks – Nitrile rubber (NBR): -30~100; Use a metal bellows mechanical seal if the safe operating temperature is exceeded. Silicone rubber (MVQ): -40~200; Ethylene-propylene rubber (EPR): -10~160; Fluororubber (FPM): -30~180; Polytetrafluoroethylene (PTFE): -100~220. V. Special properties of the medium. 1. Viscosity: For low-viscosity media that are prone to dry friction, a balanced type is recommended. For high-viscosity media, a forced-drive mechanism is recommended. 2. Corrosion and chemical solvents: a. For strong corrosion, an externally mounted PTFE bellows seal is recommended. b. The suitability of auxiliary seals in different chemical media is shown in the table below: Material; Application: Nitrile rubber (NBR): Mineral oil, gasoline, volatile oils, potassium carbonate, potassium hydroxide, water, phosphoric acid, etc.; Silicone rubber (MVQ): Butanol, minimally swelling mineral oils, weak acids, weak bases, ammonia water, etc.; Ethylene propylene rubber (EPR): Propanol, alkalis, sulfur dioxide, potassium dichromate, hydrogen peroxide, ammonia water, etc.; Fluororubber (FPM): Hot oil, steam, inorganic acids, butanol, chlorinated solvents, etc.; Chloroprene rubber (FCO): Freon; Polytetrafluoroethylene (PTFE): Acids, alkalis, solvents, and various other media. 3. In the presence of suspended solid particles: The materials for the rotating and stationary rings should be tungsten carbide/tungsten carbide or silicon carbide/silicon carbide. When particles are likely to block the sealing chamber, it is necessary to use a flushing fluid that has been filtered or separated using auxiliary devices to clean the end faces. 4. Highly toxic or gaseous media: A double-end face mechanical seal is recommended.

The mechanical seal of the pump is designed and manufactured by the pump manufacturer; it can be selected or the pump can be modified accordingly.

There are generally two types of seals: mechanical seals and packing seals. For mechanical seals used in the petrochemical industry, it is recommended to refer to API682.

Mechanical seals are still the most widely used nowadays!

There are three types of seals: mechanical seals, packing seals, and dry gas seals. Dry gas seals are generally used in compressors, while packing seals and mechanical seals are more commonly used in pumps

Mechanical seals are the most commonly used and most mature type for packing seals

There are mechanical seals and packing seals. Advantages and disadvantages of packing seals: Advantages: simple and easy to implement. Disadvantages: high maintenance requirements, significant energy loss, and a certain degree of leakage; therefore, they are not suitable for sealing applications involving flammable, explosive, toxic, or important liquids. Advantages and disadvantages of packing seals: Advantages: Good sealing performance, long service life, low power consumption, and greater safety especially when transporting liquids that are explosive or toxic. Disadvantages: Complex structure, high precision requirements, high cost, and inconvenient for loading, unloading, and replacing parts

We use centrifugal sealing, eliminating the hassle of mechanical seals; a single pump can operate for 2 years without any maintenance.

The shaft seal serves to provide a seal between the rotating pump shaft and the stationary pump casing, with the main purpose of preventing high-pressure liquid from leaking out of the pump and stopping air from entering it. Common shaft seal types used in centrifugal pumps include rubber seals with a skeleton, packing seals, mechanical seals, and floating ring seals. Each of these types has its own characteristics: Rubber seals with a skeleton: This type of seal uses the elasticity of rubber and spring pressure to press the sealing ring tightly against the shaft (shaft sleeve). Its advantages are a simple structure, small size, and relatively good sealing performance； The disadvantages are that the inner diameter of the sealed bowl tends to deviate from the specified values, the shaft is tightened too much resulting in high energy consumption; furthermore, its heat resistance and corrosion resistance are inadequate, leading to a short service life and strict installation requirements ； Packing seal: This type of seal generally consists of a packing gland, packing rings, and a packing compression nut. Sealing is achieved through the contact with the outer circular surface of the stuffing box shaft (bushing), featuring a simple structure, low cost, and easy installation. The disadvantages are: high power consumption, severe wear of the shaft (shaft sleeve), which can lead to heating and smoking, and even burn out the packing and shaft sleeve; it is not suitable for use in high-temperature, flammable, explosive, or corrosive environments. Mechanical seal: (face seal) It consists of a rotating ring, a stationary ring, springs, a thrust ring, a drive seat, and dynamic and static sealing rings. Sealing is achieved through friction and compression resulting from the tight fit between the rotating and stationary rings. The advantages of mechanical seals are good sealing performance, long service life, low power consumption, and wide applicability. The disadvantages are complex manufacturing, high cost, and high installation requirements. Floating ring seal: The floating ring seal achieves axial sealing through the contact between the floating ring and the end surfaces of the floating sleeve.

What type of seal is a centrifugal seal? I’m hearing about it for the first time

Mechanical seals are the most commonly used, while packing seals may be employed on water pumps