Danfoss SVA-S SS 65 Manuel d'installation - Page 2

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ENGLISH

Installation

Refrigerants

Applicable to HCFC, HFC, R717 (Ammonia),

R744 (CO

) and all flammable refrigerants.

The valve is only recommended for use in closed

circuits. For further information please contact

Danfoss.

Pressure and temperature range

SVA-S/L SS (DN 15-65) 52 bar (754 psi)

SVA-S/L SS (DN 80-125) 50 bar (725 psi) at

–60°C/+150°C (–76°F/+302°F).

Installation

The valve must be installed with the spindle

vertically upwards or in horizontal position (fig.

1). Valves should be opened by hand without the

use of tools or other devices (fig. 3). The valve is

designed to withstand a high internal pressure.

However, the piping system should be designed

to avoid liquid traps and reduce the risk of

hydraulic pressure caused by thermal expansion.

It must be ensured that the valve is protected

from pressure transients like "liquid hammer" in

the system.

Attention!

SVA-S/L SS are shut-off valves and must always

be either fully closed or fully open. Half open

positions are not allowed.

Recommended flow direction

To achieve optimum flow conditions, the valve

should be installed with the flow towards the

valve cone as indicated by the arrow on the side

of the valve body (fig. 2). Flow in the opposite

direction is also acceptable (fig. 2), but slightly

reduces the k

- / C

value.

Welding

The bonnet should be removed before welding

(fig. 4) to prevent damage to the sealing parts in

the packing gland and between the valve body

and bonnet, as well as the teflon gasket in the

valve seat.

Be careful not to damage the teflon cone ring

and make sure the complete bonnet is protected

from dirt and water while removed.

Removing the bonnet can be omitted provided

that: The temperature in the area between the

valve body and bonnet during welding does not

exceed +150°C/+302°F. This temperature

depends on the welding method as well as on

any cooling of the valve body during the

welding itself. (Cooling can be ensured by, for

example, wrapping a wet cloth around the valve

body.) Make sure that no dirt, welding debris etc.

get into the valve during the welding procedure.

Only materials and welding methods,

compatible with the valve housing material,

must be welded to the valve housing. The valve

housing must be free from stresses (external

loads) after installation.

The valve should be cleaned internally to

remove welding debris on completion of

welding and before the valve is reassembled.

Avoid welding debris and dirt in the threads of

the housing and the bonnet.

Do NOT remove or service the dark colored

grease between the spindle thread and the

bonnet. In case the grease has been

contaminated with dirt, debris, particles or water

the complete top part must be replaced.

Stop valves must not be mounted in systems

where the outlet side of the valve is open to

atmosphere. The outlet side of the valve must

always be connected to the system or properly

capped off, for example with a welded-on end

plate.

Assembly

Remove welding debris and any dirt from pipes

and valve body before assembly. Check that the

cone has been fully screwed back towards the

bonnet before it is replaced in the valve body

(fig. 5a).

Tightening

Tighten the bonnet with a torque wrench, to the

values indicated in the table (fig. 5b).

Please note that the table (fig. 5b) containing

maximum torque must be adhered to and never

exceeded.

Colours and identification

The SVA valves are painted with a red oxide

primer in the factory. Precise identification of the

valve is made via the ID ring at the top of the

bonnet, as well as by the stamping on the valve

body. The external surface of the valve housing

must be guarded against corrosion with a

suitable protective coating after installation and

assembly.

Protection of the ID ring when repainting the

valve is recommended.

Maintenance

Packing gland

When performing service and mainte-nance,

replace the complete packing gland only, which

is available as a spare part. As a general rule, the

packing gland must not be removed if there is

internal pressure in the valve. However, if the

following precautionary measures are taken, the

packing gland can be removed with the valve

still under pressure:

Backseating (fig. 6)

To backseat the valve, turn the spindle counter-

clockwise until the valve is fully open.

Pressure equalization (fig. 7)

In some cases, pressure forms behind the

packing gland. Hence a handwheel or similar

should be fastened on top of the spindle while

the pressure is equal-ized. The pressure can be

equalized by slowly screwing out the gland.

Removal of packing gland (fig. 8)

Handwheel and packing gland can now be

removed.

Dismantling the valve (fig. 9)

Do not remove the bonnet while the valve is still

under pressure.

Check that the flat gasket (pos. A) has not

been damaged.

Check that the spindle is free of scratches

and impact marks.

If the teflon cone ring has been damaged,

the whole cone assembly must be replaced.

Replacement of the cone (fig. 9)

Unscrew the cone screw (pos. B) with an Allen

key.

SVA-S/L SS 15-40 ........................................ 2.0 mm A/F

SVA-S/L SS 50-65 ........................................ 2.5 mm A/F

SVA-S/L SS 80-100 .........................................4 mm A/F

SVA-S/L SS 125 ...............................................5 mm A/F

(An Allen key is included in the Danfoss

Industrial Refrigeration gasket set).

To remove the balls compress the disk spring

(pos. D) and remove the balls (pos. C).

Number of balls in pos. C:

SVA-S/L SS 15-20 ..................................................10 pcs.

SVA-S/L SS 25-65 ..................................................14 pcs.

SVA-S/L SS 80-125 ..............................................13 pcs.

The cone can then be removed. Place the new

cone on the spindle and remember to place the

disk spring (pos. D) between the spindle and

the cone. Compress the disk spring and replace

the balls (pos. C). Refit the cone screw in again

using Loctite No. 648. to ensure that the screw is

properly fastened.

Do NOT remove or service the dark colored

grease between the spindle thread and

the bonnet. In case the grease has been

contaminated with dirt, debris, particles or water

the complete top part must be replaced.

Replacement of backseat seal (fig. 10)

For sizes DN 80-125 only:

The valve backseat is a special teflon ring. If

this is damaged, it must be replaced. Screw the

spindle out of the bonnet. Carefully remove the

original backseat seal and mount a new one

in the angled contact surface directly inside

the opening in the bonnet. Avoid folding and

damage to the teflon ring, or damage to the

contact surface at the top of the valve during

assembly.

Assembly

Remove any dirt from the body before the valve

is assembled. Check that the cone has been

screwed back towards the bonnet before it is

replaced in the valve body (fig. 5a).

Tightening

Tighten the bonnet with a torque wrench, to the

values indicated in the table (fig. 5b).

Please note that the table (fig. 5b) containing

maximum torque must be adhered to and never

exceeded.

Tighten the packing gland with a torque wrench,

to the values indicated in the table (fig. 11).

Use only original Danfoss parts, including

packing glands, sealing parts and gaskets for

replacement. Materials of new parts are certified

for the relevant refrigerant.

In cases of doubt, please contact Danfoss.

Danfoss accepts no responsibility for errors

and omissions. Danfoss Industrial Refrigeration

reserves the right to make changes to products

and specifications without prior notice.

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