Uni-directional Knife gate valve Type S21 with monobloc enclosure

Type S21 - Uni-directional​​​ Knife gate valve

Description: Uni-directional Knife gate valve


The ACI knife gate valve type S21 consists of a cast monoblock body and is tight in one direction. Its design guarantees a high flow rate with minimal pressure loss.


Internal guide bushes serve to stabilize the gate and improve the sliding behavior. We supply the Knife-gate valves with rising or non-rising stem.


The standard execution is available as wafer type version for installation between flanges PN 10 / 16. The "Lug-Type" version has tapped holes and can therefore be used as an end valve.

The sealing is on one side between body and gate, on the side facing the pressure. The direction of flow is indicated by an arrow.


Depending on the application area, there are basically two different sealing systems:

  • Metal - metal: there is no absolute tightness, the estimated leakage rate is 1.5% (at water as test liquid)
  • Rubber - metal sealing; in this case a sealing ring is clamped by a stainless steel fastening ring on the inside of the body.

To protect the seal and the fastening ring from abrasion, a conical deflector can be mounted to direct the flow of media away from the housing into the middle of the valve.

ACI gate valves type S21 are available in nominal sizes DN 50 to DN 2000; larger nominal sizes are available on request.

These ACI knife gate valves are designed for installation between flanges according to EN 1092-1 PN 10. Alternatively, flange connection dimensions acc. to EN 1092-1 PN 6 or PN 25, ASME B16.5 Class 150, BS or JIS are also available.


Applied standards:

‐ Machinery Directive: DIRECTIVE 2006/42/EC (MACHINES).

‐ Pressure Equipment Directive: DIRECTIVE 2014/68/EU (PED) ART. 4, P.3

‐ Directive on use in potentially explosive atmospheres (optional): DIR 2014/34/EU (ATEX) CAT.3 AREA 2 and 22 GD.

For information on categories and areas, please contact Technical Support.


All valves are hydrostatically tested in accordance with EN 12266. The test reports and material test certificates acc. to EN 10204-3.1 can be provided on request.The pressure test is performed as follows:

Body test = operating pressure x 1.5

Closing test = operating pressure x 1.1


This ACI knife gate valve type S21 is suitable for use with liquids containing a maximum of 5% dissolved solids. However, it is also used e.g. for filling / discharging dry solids and bulk materials; in this case, however, it is recommended to mount the housing in the opposite direction to the direction of flow.

Any deposits are thus flushed out of the cavity below the gate.

ACI Knife Gate Valves S21 are mainly used in the paper and pulp industry, mining industry, chemical industry, for pump and waste water technology, food and beverage industry, filling and unloading stations.

Available body materials are GG-25 / GJL 250, GGG 40 / GJS-400 or stainless steel 1.4408. Standard material for the stem is stainless steel AISI 303 / 1.4305, the gate is made of AISI 304 / 1.4301. On request, stem and gate can also be supplied in other grades, e.g. of 1.4571 or duplex. The support plates are made of steel. If the valve is equipped with an actuator, the support plates are executed as an hand protection. With an EPOXY coating (in blue - RAL 5015), all components that are not made of stainless steel are protected against corrosion. The layer thickness is approx. 80 µm. Stuffing box packings and seals can be supplied in a variety of materials to suit your application, such as NBR, EPDM, FKM, PTFE, etc.

ACI Knife-gate valves type S21 are available with either handwheel, gearbox or chain wheel. Equipped with a quick closing lever, these valves are available up to DN 300. In addition, the valves are also available with pneumatic, hydraulic or electric actuators.


Available options:

  • Special materials, e.g. DUPLEX
  • Knife gate valve with rectangular passage
  • Pentagonal- or V-Port for regulation
  • Conical deflector for use with abrasive media
  • Stem extension
  • Encapsulated top for underground installation
  • Knife gate valves with through-going gate

Technical Data

Material:

Body:
GG-25 / GJL 250, GGG 40 / GJS-400 or SS 1.4408

Gate:
AISI 304 / 1.4301

Stem:
AISI 303 / 1.4305

Form:

Uni-directional Knife gate valve, EPOXY coating (in blue - RAL 5015), quick closing lever (from DN50 - DN300)

Nominal diameter:

DN50 - DN2000

Nominal pressure:

PN10

Options:

  • Special materials, e.g. DUPLEX
  • Knife gate valve with rectangular passage
  • Pentagonal- or V-Port for regulation
  • Conical deflector for use with abrasive media
  • Stem extension
  • Encapsulated top for underground installation
  • Knife gate valves with through-going gate
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