YALAN Frequently Asked Questions

Frequently Asked Questions

Frequently Asked Questions

1. Q: What is mechanical seal and what is the situation that my device or equipment would need to use a mechanical seal?

A: A mechanical seal is a device that helps join systems or mechanisms together by preventing leakage (for instance, in a plumbing system), containing pressure, or excluding contamination. Normally when you have a device that contains a rotating part, such as a shaft, and at the meanwhile you need one side of the shaft to have no leakage of liquid or gas from the other side, you would need a mechanical seal in your system.

With and without a mechanical seal


2. Q: How is a mechanical seal constructed?

A: All mechanical seals have these 3 basic sets of parts, which are:

  • A set of primary seal faces, including one rotary face and one stationary face, also called seal ring and insert.
  • A set of secondary seals, also known as shaft pickings and insert mountings such as O-rings, wedges and V-rings.
  • Other mechanical seal hardware, such as gland rings, collars, compression rings, pins, springs (normally 3 types, wave springs, single springs, multiple/small springs) and bellows (normally 2 types, rubber bellows and metal bellows).

3. Q: Why shall I use a mechanical seal?

A: In the past and even nowadays, many rotary devices have been using packing (as known as Gland Packing too) but more and more devices have been starting to use mechanical seals, due to the advantages of mechanical seals below:

  • There will be no visible leak. However, there will be leak vapor, which is difficult to be prevented, such as half teaspoon one day at normal operating pressures and temperatures.
  • Advanced cartridge seal design can reduce and even prevent damage to the pump shafts and sleeves.
  • Daily maintenance will be reduced because mechanical seals normally have internal springs and they can have self-adjusting when faces wear.
  • Comparing to packing, mechanical seals have smaller pressure to faces (less resistance) so that they cost less power for the whole system to drive the shafts.
  • Less bearing contamination will be caused, because the lubricant does not become affected by seal leakage or washout.
  • With special anti-corrosion design and materials in mechanical seals, equipment that uses mechanical seals will suffers much less from corrosion.
  • For vacuum pumps, packing can never be used because air can be drawn into the pumps. So mechanical seal is a better choice here.
  • Longer life time and less time for installing new mechanical seals will cost less money and reduce the time of equipment downtime.

4. Q: What kind of devices would need to use mechanical seals?

A: Basically any rotating device that will need to seal possible leakage is able to equip mechanical seals. On our website we are categorizing all mechanical seal products into several categories according to their usages, shown as below:

  • Clean Water, Vacuum & Circulating Pump Seals;
  • Chemical & Centrifugal Pump/Compressor Seals;
  • Agitation Equipment & Reaction Kettle Seals;
  • Sewage Pump Seals;
  • Slurry Pump Seals;
  • Paper-making Equipment & Pressure Screen Seals;
  • High-temperature Oil Pump Seals.

5. Q: What are the advantages and limitations of multi-spring mechanical seals?

A: The advantages of multi-spring mechanical seals are:

  • Compact comparing with single spring mechanical seals.
  • Spring load uniform, for instance, uniform face loading.
  • Can be running with higher speed than single spring seals.
  • Not requiring different spring sizes for different seal sizes.

The limitations are:

  • Higher cost.
  • Spring clocking may happen when the mediums are dirty fluids.

6. Q: Why choose YALAN Seals?

A: The factory of YALAN Mechanical Seals was founded in 1993. YALAN Seals has produced over 3,000 different types of mechanical seals. YALAN has a dedicated and experienced design team serving over 200 companies within and out of China for standard and custom mechanical seals. Some of our famous and long-term clients are: Giti Tires, RSP Industrial Pumps, Evonik Industrials, Asia Pulp and Paper (APP), JAC Motors, Lucky Film, BBCA Group, China National Salt Industry Corporation, China National Cereals, Oils and Foodstuffs Corporation and China Huaneng Group.

All products and production procedures of YALAN Seals are certificated by ISO9001:2015.

Mechanical seals designed or manufactured by YALAN have similar performances to other products of worldwide well-known companies such as EagleBurgmann, John Crane, ASE and EKK. The operating lifetime of YALAN products can reach at least 80% of those products from these big brands, since we are using the same material vendors for most of our products as EagleBurgmann and John Crane China factories, while prices of YALAN mechanical seals are normally only 40% to 60% of the products from these famous companies. With great after-sales services, YALAN Seals, as great replacement solutions, has huge comparative advantages.

YALAN Seals is very confident in its product quality and basing on that, we offer half/1/2 years unlimited product quality warranty to our overseas clients. For more details about our product quality warranty, please check here.

With over 25 years of mechanical seal designing and manufacturing experiences, YALAN Seals has now over 28 patents and inventions. For more details please check here. YALAN Seals production facility is also one of the 200 companies that have National Industrial Production Permission for Mechanical Seals (in total over 10,000 mechanical seal factories in China, but only around 200 of them are legally producing mechanical seals with this permission).


7. Q: What is Gland Packing?

A: Gland packing is the traditional solution to seal against fluids. It is still a very cost and performance effective sealing solution even now, for where small leakage does not cause real problems.

Gland packing makes a series of pieces or “rings” installed around the shaft into the stuffing box and they are compressed together tightly by the packing gland. These pieces or rings create a difficult leak path for the fluid to leak without binding the shaft motion.

The packing materials used are normally Teflon (PTFE) and graphite. Mechanical packing normally has several components: stuffing box, packing rings, lantern ring and packing gland.

Gland Packing

8. Q: Why flushing solution is needed for some of the mechanical seals?

A: There are some purposes below for using a flushing solution on the mechanical seals:

  • To lubricate and cool mechanical seals.
  • To remove foreign particles.
  • To remove carbon deposition and engrossed materials on mating surfaces.
  • Prevent seal from dry running.
  • To maintain the operational parameters of mechanical seals.

9. Q: What are the essential requirements for proper operation of a mechanical seal?

A: There are 3 essential requirements:

  • Seal faces must be flat and polished.
  • Seal faces must be installed perpendicular to the shaft.
  • Spring force must be sufficient to maintain contact of the faces.

YALAN has many types of seal face material combinations. To check and understand what different kinds of operating conditions of different seal face materials, please check our chart of seal face materials and features.


YALAN Product Catalog Download

Mechanical seal products of YALAN will keep updated and you can always download the latest version here.

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