134 MDGS Mechanical Seals for Pumps Pusher Seals

(1)Features
• Gas-lubricated
• Bi-directional
• Ready-to-fit cartridge unit
• Single, double, tandem seal and tandem with intermediate labyrinth available

(2)Operating range (see note on page 1)
Shaft diameter: d1 = 40 ... 280 mm (1.57" ... 8.66")
Pressure: p = 0 ... 50 bar (0 ... 725 PSI)
Temperature: t = -20 °C ... 200 °C (-4 °F ... +392 °F)
Sliding velocity: vg = 0.6 ... 200 m/s (2 ... 656 ft/s)

(3)Advantages
The rotating ductile ring with a high performance coating
as the main distinctive feature to other dry gas seals
excludes any ring disintegration in case of seal failure. The
required radial space of this seal is smaller than existing
Dry Gas Seals and the seal fits into small seal cavities, as
you find them in process gas screw compressors, without
making any compromise with regard to seal reliability.
The stationary spring loaded unit is supplied as a sub
cartridge in combination with a rotating ductile seat
integrating secondary functions such as centring and
secondary sealing by means of an O-Ring allow the use
of this seal as a component sea

(4)Item          Description
1                Seal face, stationary
2                Seat, rotating
3                Thrust ring
4                Spring
5                Housing of standardized stationary sub-cartridge
6                Shaft sleeve, intermediate sleeve
7, 8            Housing (adapted in size to the installation space)
9                Carbon ring type separation seal

  10               Intermediate labyrinth
A                Product flushing
B                Flare
C                Buffer gas
D                Separating gas
S                 Vent

(5)Materials
Seal face: Carbon graphite impregnated
Seat: Ductile stainless steel with DM-TiN coating
Secondary seals: FKM (V) or other materials depending
on product gas composition
Metal parts: 1.4006 or other stainless steels.

(6)Standards and approvals
• NACE

(7)Recommended applications
• Oil and gas industry
• Refining technology
• Petrochemical industry
• Hydrocarbon gas
• Ammonia
• Nitrogen
• Refrigerants
• Air
• Centrifugal compressors
• Dry process gas screw compressors
• Blowers

(8)Product variants
MDGS Tandem seal
Application: Where small product leakages of process
gas are admissible, e.g. on gas pipeline compressors.
Seal on the atmosphere side acting as a safety seal.
The tandem arrangement provides a particularly high degree
of operational safety. The seal on the product side and the
seal on the atmosphere side are able to absorb the
complete pressure differential. Under normal operating
conditions the full pressure is reduced only by the seal
on the product side. The space between the seal on the
product side and the seal on the atmosphere side is cleared
by a connection "B" to the primary vent (flare). The pressure
differential to be sealed by the seal on the atmosphere side
equals the primary vent pressure, so the leakage to the
secondary vent (atmosphere) is very low. If the main seal
fails, the second seal acts as a safety seal.

MDGS Tandem seal with intermediate labyrinth
Application: Where product leakages to the atmosphere
as well as buffer gas leakages to the product are
inadmissible, e.g. on H2, ethylene or propylene compressors. With this version the product pressure to
be sealed is reduced via the seal on the product side.
The entire process gas leakage is discharged via
connection "B" to the primary vent. The seal on the
atmosphere side is pressurized with buffer gas (nitrogen)
via connection "C". The pressure of the buffer gas
ensures that a nitrogen flows via the labyrinth to the
flare/vent outlet

MDGS Dual seal
Application: Where product leakages to the atmosphere
are inadmissible and tandem arrangements are not
suitable because of too small product gas pressures.
Buffer gas leakages into the product must be admissible
(buffer pressure p3 > p1). This seal is used when a
neutral buffer gas of suitable pressure is available. Typical
applications are to be found mainly in the chemical
industry, e.g. on HC gas compressors. A buffer gas, e.g.
nitrogen, is fed between the seals via connection "C" at a
higher pressure than the product pressure. One part of the
buffer gas leakage escapes to the atmosphere side and
the other part to the product.

Dimensions in mm

We have large stock, so our delivery  is very fast.
For example,if products are standarded, the delivery time is one week.
Our company and factory addrss: Ningbo City, Zhejiang  Province,China.
Our city has a large port and an airport, so its transportation is very convenient.

Question1: What are the prices of your products?
  Answer: For each model, the unit price is listed on the website, but what is displayed on the website is only the average market price. For specific models, you can contact us for further consultation and negotiation.

  Question 2: Are you a factory or a trade company?
  Answer: We are a factory with top sales for the trade service.
Question 3: What is the minimum order quantity for each order?
  Answer: For products of regular models, the minimum order quantity is at least five. We welcome you to test the quality of our products and services through placing trial orders. Looking forward to the long-term cooperation with you.

  Question4: What is your company's service tenet?
  Answer: Quality first, service upmost. We promises that if there is any problem with the quality of the product, or if the product is damaged during the transportation, our company will be responsible for compensation, regardless of the ordder turnover value.

  Question5: Can I try to get a SAMPLE before the order?
  Answer: Sure. Our company will provide you with samples for free, but you will have to pay for the international delivery (freight collect payment).