Magnetic drive pumps and mechanical seal pumps

How do seal and sealless pumps work?

When selecting a pump where chemicals, acids and corrosive liquids are involved it is necessary to choose the right pump design according to the application and the customer’s needs. Armek can supply both mechanical seal and sealless pumps. Here you can find their differences and advantages.

Magnetic drive pumps

Mag drive pumps have a particular sealless design where the hydraulic part is hermetically closed with no contact with the motor. The external magnet placed on the drive shaft transmits the motion to the internal magnet connected to the impeller which rotates and moves the fluid through the pump. The external magnet and inner magnet are separated by a rear casing that creates a hermetic containment of the liquid which has no access to the outside. Thanks to this design the pump is 100% leak-free and emission free and a perfect solution when dealing with acids.
Pumps series HTM PP/PVDFHTM SS316HTT and HTA are manufactured by Armek with the mag drive system.

Main features of mag drive pumps

  1. Magnetic drive pumps have a special hermetic pump design that prevents any leakage of fluid and dangerous emissions that could be very dangerous for people and for the environment in case of chemicals, corrosive liquids, explosive and flammable fluids. So magnetic drive pumps allow following strict environmental and safety objectives required by many regulations.  You shouldn’t forget also that some liquids could be very expensive and their leakage due to a seal failure may cause high unnecessary extra costs.
  2. Thanks to their simple design our magnetic drive pumps guarantee reliability and very low maintenance. With normal working conditions, these pumps can last for more than a decade and work without any kind of repair. Therefore their life cost is highly reduced and no plant shutdowns are necessary.
  3. The coupling of the pump with the motor is very easy because there is no need for a motor/pump alignment.
  4. Magnetic drive pumps can work only with clean liquids without solids in suspension. In case of solids, the right solution is a mechanical seal pump

Mechanical seal pumps

Mechanical seal centrifugal pumps are perfect for applications involving solids in the liquid because their design with open impeller allows them to pump dirty liquids and fluids with high viscosity. The seal in mechanical seal pumps is composed of a static ring and a rotating ring placed on the pump shaft which is directly coupled to the motor shaft. The two surfaces sliding together need to be lubricated and the seal lubricant is the liquid itself that is being pumped.
Armek pumps series HCO are designed with a mechanical seal system.

Main features of mechanical seal pumps

  1. Well known pumping system used in chemical industries for decades.
  2. Mechanical seal pumps are the right solution for chemical applications containing solids in the liquid (for example wastewater treatments) because their design with open impeller allows them to pump liquids containing up to 5% of solids 
  3. The cost of this kind of pumps is lower in comparison with mag drive pumps so, if the financial aspect is critical when choosing the pump, a mechanical seal pump may be the right choice
  4. Periodical maintenance is required to check the status of the seal and avoid pump failures.

Pump materials

Armek chemical pumps are used with fluids that can be corrosive and very aggressive, so it’s really important to use highly resistant and compatible materials. As standard materials for our pumps, we use thermoplastic materials Polypropylene (PP), PVDF and stainless steel AISI 316.
Every material has its own properties and characteristics which make it suitable for transferring different acids. So it’s really important to choose the right pump material for every chemical application.
Polypropylene (PP)

Polypropylene is well known with the name Moplen (™)
It’s a thermoplastic material extremely resistant to many solvents, bases and acids such as for example acetone, caustic soda and chloridric acid.
It’s not suitable for concentrated, oxidizing acids.
It’s used in many different industries for parts subjected to relatively modest forces.
Temperature range for PP pumps is from 0° to 70°C.

Polyvinylidene fluoride (PVDF)

It’s a thermoplastic material of the fluoropolymer family and it’s generally used in special applications requiring high purity, strength, and resistance to solvents, acids, saline solutions, alkali and bases.
It’s mainly used with liquids such as for example sodium hypochlorite, concentrated sulfuric acid, nitric acid, gasoline.
It doesn’t undergo deformation under loads and has a high mechanical resistance.
Temperature range for PVDF pumps is from 0° to 90°C.

Stainless steel AISI316

It’s a metallic material used when both the properties of steel and the resistance to corrosion are required.
Particularly indicated for pumps working with high temperature liquids, oils, kerosene, alcohols.
It’s used to pump acids up to a maximum temperature of 160°C