Danfoss Liquid level regulating valves types SV1-3 and SV4 Floating ball valves Design / Function

SV 1 – 3 float has 2 different pilot connections:S-port (series connection with PMFH) or P-port(parallel connection with the PMFH).

P-port:

When using the P-port, it is possible to force open the PMFH valve to a fully open position. This is practical for service purposes or to confirm if the float has sufficient capacity for the PMFH and the operating conditions. However, when P-port connection is used it is possible to overfill a system due to constant bleeding or unautorised tampering. In this case, it is advisable to introduce a shut off when the liquid level reaches a preset point. Shut off can be done via an electrical switch if an EVM valve is mounted in the SII port in the top of the PMFH. It is only advisable to use the P-port at low pressure difference.

S-port:

The S-port offers the advantage of a preorifice which divides the pressure drop and any wear possibility due to cavitation. S-port connection must be used at high pressure differences, dp > 10 bar (145 psi). The K v (C v ) value of the SV is higher using P-port than using S-port. A higher P-band can thus be obtained.

Danfoss Liquid level regulating valves types SV1-3 and SV4 Floating ball valves Sizing

Sizing example for PMFL

Refrigerant

R 717 (NH 3 )

Evaporator capacity

Q e = 600 kW

Evaporating temperature

t e = -10 °C (∼ p e = 2.9 bar abs.)

Condensing temperature

t c = 30 °C (∼ p c = 11.9 bar abs.)

Liquid temperature ahead of valve

t l = 20 °C at max. capacity

Subcooling

∆t sub = t c - t l = 30 - 20 °C = 10 K

Calculations do not take into account pressure

loss in pipelines.

Pressure drop across valve

∆p = p c - p e = 11.9 - 2.9 bar = 9 bar

Correction factor for 10 K subcooling

0.98

Corrected capacity

600 kW × 0.98 = 588 kW

The corrected capacity can be found in the

capacity table. It will be seen from the table that

valve type PMFL 80-4 should be chosen.

Refering to “ordering table”, code number

027F0053 can be found.

For details of flanges, accessories and pilot valve,

see the ordering table.

Since ∆p = 9 bar and ∆t sub = 10 K, it will be

seen from the “C/w strong spring set” for PMFL

that a “STRONG” spring set must be used. The

pilot line is connected to SV at connection S.

In the ordering table the code number for the

spring set can be found: 027F0118.

Sizing example for PMFH

Refrigerant

R 717 (NH 3 )

Evaporator capacity

Q e = 2200 kW

Evaporating temperature

t e = -10 °C (∼ p e = 2.9 bar abs.)

Condensing temperature

t c = 30 °C (∼ 11.9 bar abs.)

Liquid temperature ahead of valve

t l = 20 °C

Subcooling

∆t sub = t c - t l = 30 - 20 °C = 10 K

Calculations do not take into account pressure

loss in pipelines.

Pressure drop across valve

∆p = p c - p e = 11.9 - 2.9 bar = 9 bar

Correction factor for 10 K subcooling

0.98

Corrected capacity

2200 kW × 0.98 = 2156 kW

The corrected capacity can be found in the

capacity table. It will be seen from the table that

valve type PMFH 80-7 should be chosen.

In the ordering table the code number for the

valve can be found: 027F3060 for CE-approved

valve.

For details of flanges, accessories and pilot

valve, see the ordering table.

Type Connection Code no.

Float pilot valve

type SV

Balance tube

liquid / vapour

Pilot line SV 1:

027B2021

027B2021CE  2 )

SV 3:

027B2023

027B2023CE  2 )

1 in.

weld

Ø 6.5 / Ø 10 mm

weld  1 )

1 )  3 ⁄ 8 in. flare connection can be supplied under code no. 027B2033.

2 ) Approved and CE-marked in accordance with Pressure Equipment Directive - 97/23/EC.

Valve type

Orifice

diameter

Code no.

Code no.

without

housing 1 )

SV 4 Ø 3.0 mm 027B2024  2 ) 027B2014  2