Correct Choice of Gate

 

Slide Gate

To correctly choose a slide gate, the following need to be established: 

•  Size.
• Pressure.
• Tightness requirements.
• What is the function of the gate?
• How often will the gate operate – open or close?
• What degree of serviceability does the user want?
• The substance in which the gate must operate.
• Choice of Material.

How is the gate to be driven or moved? Is it to be:

• Operated by hand.
• Electrically driven: On – Off.
• Electrically driven: Regulated 4 – 20 mA.
• Pneumatically driven.
• Hydraulically driven.
If hydraulics is chosen as the driving device, it is possible to install an automatic function for opening or closing, which can be used as a safety function as well.

Where in the structure is the gate placed:

If the gate is placed on a wall with ample space in all directions, all gate types can be used.
If, however, the gate is placed at the bottom of a structure and you also want water and impurities to pass unrestricted through the gate, a type of gate, that can meet the desired requirements, must be chosen.
If the gate can get submerged, it is necessary to consider where to place the driving device to open and close the gate.

Slide gate, tightness acc. to DIN 19569-4

Table 1: Classes of tightness with examples for use.

Class Maximum allowed leakage in litres per sec. per metre gasket length (l/s/m). Examples for use with pressure on front Recommended gate types from Gerhardt Christensen
1 over 0,3 til 1 – Plank Gate
– Distribution gate
Type 3
2 over 0,1 til 0,3 – Gate

– Plate

Type 1
3 over 0,05 til 0,1 – Non-return flaps

– Slide Gate

Type KV
Type 7.3 – Type 5
4 over 0,02 til 0,05 – Slide Gate Type 7.4 – Type II
Type II L
5 til 0,02 – Slide Gate (Drip-tight) Type II – Type II L
NOTE: For pressure on the rear, a higher class for leakages must generally be applied.

How tight must a gate be? Tight, a little leaky, pretty tight, drip-tight or How tight does the

gate, which is to be used, need to be?

In the following, it will be made probable, what tight is.

A tap over a hand basin supplies an amount of water equal to 0.1 l/s = 6 litres/min

How much leakage is acceptable from a slide gate?

Example:

Slide gate class 4, inside measure 500 x 500 mm.

You can find the lower and upper limits for leakage for class 4 in the table.

Lower limit = 0.02 l/s/m, upper = 0.05 l/s/m.

The leakage must be within:

Lower limit 0.02 x (0.5 x 4) = 0.04 litres/sec. = 2.4 litres/min to

Upper limit 0.05 x (0.5 x 4) = 0.1 litres/sec. = 6.0 litres/min

Example:

Slide gate class 4, inside measure 1,000 x 1,000 mm

You can find the lower and upper limits for leakage for class 4 in the table.

Lower = 0.02 l/s/m, upper = 0.05 l/s/m.

The leakage must be within:

Lower limit 0.02 x (1.0 x 4) = 0.08 litres/sec. = 4.8 litres/min to

Upper limit 0.05 x (1.0 x 4) = 0.2 litres/sec. = 12 litres/min

 

                                                                                   Slide gate, choice of material

 

Type of gate Gate frame Gate plate Spindle Spindle nut PP – guideway Gasket
Blocking gate Type 1 RS Alu/RS PEHD
Plank gate Type 3 RS Alu/RS A4 RS PEHD N250/N506
Drop gate Type 5 RS RS A4 Bronze RG7 PEHD N250
Slide gate Type 7.3 RS RS A4 Bronze RG7 PEHD N250/N506
Slide gate Type 7.4 RS RS A4 Bronze RG7 PEHD N250/N506
Slide gate Type II RS RS A4 Bronze RG7 NBR
Slide gate Type II L RS RS A4 Bronze RG7 NBR
Slide valves RS RS A4 Bronze RG7 NBR
Pivot gate RS RS A4 Bronze RG7 N250

RS: Stainless steel AISI 304 / WST 1.4301, AISI 316L / WST 1.4404, AISI 316 / WST 1.4435, AISI 316L / WST 1.4436 or as required

Alu: AlMg3 sea-water-resistant aluminium

Gerhardt Christensen A/S produces the following types of gates:
• Blocking gates Type 1
• Plank gates Type 3
• Drop gate Type 5
• Slide gates Type II
• Slide gates Type II L
• Slide gates Type 7.3
• Slide gates Type 7.4
• Slide valves
• Pivot gates