Danfoss Liquid level glasses, LLG 185 - 1550 Datasheet

Danfoss Liquid level glasses, LLG 185 - 1550 Datasheet
Data sheet
Liquid level glasses
type LLG 185 - 1550
Introduction
LLG are liquid level glasses in ductile steel
which meets the strictest requirements on
industrial and marine refrigeration
installations. The liquid level glasses are
offered in 3 different versions:
- with welding nipples (LLG)
- with stop valves equipped with caps
(LLG S)
- with stop valves and sight adapter in acrylic
glass ready for insulation on site (LLG SF).
The range of liquid level glasses is based on 3
basic liquid level glasses: LLG 185, LLG 335
and LLG 740. The other standard lengths are
combined by using variations of basic glass
lengths.
Features
Refrigerants
Applicable to all common non flammable
refrigerants including R 717 and non
corrosive gases/liquids dependent on
sealing material compatibility
Temperature range
–10/+100°C (–14/+212°F) or
–50/+30°C (–58/+86°F)
LLG produce sufficient flow areas to secure
the highest possible degree of synchronous
operation, and have a specially hardened
reflection glass for quick reading. The front
and the base frame are mounted together
from the front with countersunk allen screws.
This ensures easy insulation on site as well as
easy inspection and service, if any.
The liquid level glasses are equipped as
standard with a built-in safety system (non
return device). If a glass is damaged, the
pressure of the refrigerant will activate the
safety system and refrigerant loss will be
limited to an absolute minimum.
Equipped with boron silicate glass,
hardened by an accurately controlled heat
treatment process
Classification: To get an updated list of
certification on the products please contact
your local Danfoss Sales Company.
Maximum operating pressure: 25 bar g
(363 psi g)
ã Danfoss A/S, 05 - 2001
RD.6D.B2.02
1
Data sheet
Liquid level glasses, type LLG 185 - 1550
Design
Glass
LLG's are equipped with a boronsilicate glass,
hardened by an accurately controlled heat
treatment process. All glasses are according
to DIN 7081.
Gaskets
The glasses are equipped with a special nonasbestos carbon compound gasket which
provides superior mechanical characteristics
and a long time guarantee against service
leakage.
Connectors
LLG 590, LLG 995, LLG 1145 and LLG 1550
are joined together by 2 basic LLG’s by means
of a connector. The connector holds the two
basic glasses together by means of screws
and guiding pins, which ensures a rigid
construction.
Stop Valves/Nipples
The glasses are connected to the refrigeration
system by means of welding nipples or stop
valves. Which ever system is used, the
nipples or stop valves are screwed into a
flange, which is located in the correct position
and subsequently tightened with a seal gasket
and 4 screws.
Technical data
Refrigerants
The liquid level glasses are applicable to all
common non flammable refrigerants
including R 717 and non corrosive gases/
liquids dependent on sealing material
compatibility.
For further information please see
installation instruction for LLG.
Flammable hydrocarbons are not
recommended. For further information
please contact your local Danfoss Sales
Company..
Installation
Install the glasses on a bracket using the 4
screws supplied with the glass.
Use the threaded holes on the back of the
frame to mount the glass on a bracket (not of
Danfoss supply). Always connect the piping
after mounting on the bracket. Please note the
importance of a minimum of stress in the liquid
level glasses from the connected pipes.
Please also make sure that there is sufficient
space behind the the liquid level glasses to
ensure proper insulation, service and
inspection, etc.
For installations below –10°C (+14°F) it is
recommended to add the sight adapter to
enable reading after insulation has been
applied.
For installations below –10°C (+14°F) in R 717
plants it is recommended to use an oil column
as described in the following pages. There will
be no formation of bubbles or ice build-up in
oilfilled liquid level glasses, which may be the
case in the refrigerant-filled glasses.
The liquid sight glasses are designed to
withstand high internal pressures. However,
the piping system in general should be
designed to avoid liquid traps and reduce the
risk of hydraulic pressure caused by thermal
expansion.
Pressure range
All LLG types are designed for:
Max. operating pressure 25 bar g(363 psi g)
Strength test: 50 bar g (725 psi g)
Leakage test: at 25 bar g (363 psi g).
Temperature range
The liquid level glasses are applicable to the
above mentioned refrigerants within the
temperature range of:
–10/+100°C (+14/+212°F) for the LLG types
with safety system with welding nipples and
the LLG S types with safety system with
stop valves.
–50/+30°C (–58/+86°F) for the LLG SF type
with safety system with stop valves and
acrylic glass.
2
RD.6D.B2.02
ã Danfoss A/S, 05 - 2001
Data sheet
Liquid level glasses, type LLG 185 - 1550
Frostproof liquid level
glasses
Example 1
Refrigerant: R 717 (ammonia).
Temperature: Recommended for
temperatures below
–10°C (+14°F).
The oil will show in the liquid level glass at a
level equal to the level in the oil vessel. When
R 717 is filled into the separator or
intermediate cooler it will enter the oil vessel
and press down the oil surface.
The principle shown in fig. 1 can be used in
connection with low temperature liquid
separators or intermediate coolers when the
refrigerant is R 717 (ammonia).
The R 717 will also rise into the upper balance
pipe (B) to a level equal to the level in the
separator or intermediate cooler. As the oil
surface in the oil vessel is pressed down, the
oil will rise into the liquid level glass.
As the liquid level in the R 717 separator
varies the oil level will change simultaneously.
Oil Charging
The system is charged with synthetic oil type
SHC 226 with a specific weight, differing from
that of R 717, and (h) must be multiplied by
approximately 1.35 (the ratio of density oil to
density R 717) to calculate H.
Note:
It is important to use an oil which is not likely
to mix with R 717. The oil must have a high
viscosity index to ensure easy flowing at low
temperatures. Mobil SHC 226 of the synthetic
polyalphaolefin type has proven suitable for
this purpose.
Charge the oil vessel (volume approximate 10
litres) to a level just below the lower balancing
pipe (A) through the oil charging valve. Close
the oil charging valve.
Seperator/
Intermediate cooler
Purge
valve
Oil charging
valve
Oil vessel
Fig. 1
ã Danfoss A/S, 05 - 2001
RD.6D.B2.02
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Data sheet
Liquid level glasses, type LLG 185 - 1550
Frostproof liquid level
glasses
Example 2
Refrigerant: R 717 (ammonia).
Temperature: Recommended for
temperatures below
–10°C (+14°F).
Fig. 2 shows a frostproof liquid level glass for
an R 717 liquid separator which is placed
above ground level. The arrangement is called
a Hampsonmeter.
Due to the evaporation taking place in the
uninsulated balance pipe (ND 80/3 in.) the
pressure in this pipe will be equal to
P1 = P0 + H ´ r ´ g.
P0
H
r
g
Separator pressure .......................... N/m2
R 717 liquid level (see fig. 2) ................ m
R 717 density ................................. kg/m3
Acceleration due to gravity 9.81 ....... m/s2
The oil will rise to a level h and H can then be
calculated by multiplying h by 1.35 (the ratio of
density oil to density R 717).
Charge the oil vessel through the oil charging
valve to a level of approximately 3/4 of full
level. The level will show in the lower liquid
level glass.
Take care that the volume of the oil vessel is
sufficient to allow the oil to rise into the liquid
level glasses. When the system is operating
keep the bypass valve closed.
Note:
It is important to use an oil not likely to mix
with R 717, and having a high viscosity index
to ensure easy oil movements at low
temperatures. Mobil SHC 226 of the synthetic
polyalphaolefin type has proven suitable for
this purpose.
Oil Charging
The pressure will act on the oil surface in the
oil vessel and cause the oil to rise in the liquid
level glasses which are installed in a length of
e.g. 2 in. pipe, the top of which is connected to
the top of the seperator which is at pressure
P0.
Separator
pressure P0
uninsulated
Bypass
Oil charging
valve
Fig. 2
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RD.6D.B2.02
Purge
valve
Oil vessel
ã Danfoss A/S, 05 - 2001
Data sheet
Liquid level glasses, type LLG 185 - 1550
Material specification
LLG S and LLG SF
LLG
No.
1
2
3
4
5
6
8
10
14
15
18
19
Part
Material
DIN
ISO
ASTM
Front frame
Back frame
Sight glass
Gasket
Protective
coating for sight glass
Sight adapter
Connecting piece
O-ring
Flange
Balls
Welding nipple
Stop valve (* SVA 6 T 123)
Steel
Steel
Glass
Non-asbestos
Non-asbestos
RSt. 37.2, 17 100
RSt. 37.2, 17 100
Fe 360 B, 630
Fe 360 B, 630
Grade C, A 283
Grade C, A 283
Fe 360 B, 630
Grade C, A 283
Fe 360 B, 630
Grade C, A 283
Fe 360 B, 630
Grade C, A 283
PMMA-acrylic
Steel
RSt. 37.2, 17 100
Cloroprene (Neoprene)
Steel
RSt. 37.2, 17 100
Stainless steel
Steel
RSt. 37.2, 17 100
Steel
* See technical data for SVA stop valves.
ã Danfoss A/S, 05 - 2001
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Data sheet
Liquid level glasses, type LLG 185 - 1550
Dimensions and weights
LLG
LLG S and LLG SF
* Only for LLG SF with sight adapter.
Type
LLG 185 - 1550
LLG 185
LLG 335
LLG 590
LLG 740
LLG 995
LLG 1145
LLG 1550
1)
2)
6
mm
in.
mm
in.
mm
in.
mm
in.
mm
in.
mm
in.
mm
in.
Type LLG
Type LLG S and LLG SF
RD.6D.B2.02
A
B
C
D
Weight
185
71/4
335
131/4
590
231/4
740
291/4
995
391/4
1145
45
1550
61
255
10
405
16
660
26
810
32
1065
42
1215
473/4
1620
633/4
69
23/4
63
21/2
69 + 63
23/4 + 21/2
63
21/2
69 + 63
23/4 + 21/2
63
21/2
63
21/2
48
2
42
13/4
48 + 42
2 + 13/4
42
13/4
48 + 42
2 + 13/4
42 + 42
13/4 + 13/4
42
13/4
4.2 kg 1)
5.8 kg 2)
7.5 kg 1)
9.2 kg 2)
13.2 kg 1)
15.1 kg 2)
16.5 kg 1)
18.5 kg 2)
22.5 kg 1)
24.7 kg 2)
25.7 kg 1)
28.0 kg 2)
33.5 kg 1)
36.1 kg 2)
Specified weights are approximate values only.
ã Danfoss A/S, 05 - 2001
Data sheet
Liquid level glasses, type LLG 185 - 1550
Ordering
How to order
The table below is used to identify liquid level
glasses required.
Please note that the type codes only serve to
identify the liquid level glasses, some of which
may not form part of the standard product
range.
For further information please contact your
local Danfoss Sales Company..
Example for type codes
LLG 740 SF
Type codes
Valve type
Nominal size in mm
Equipment
LLG
185
335
590
740
995
1145
1550
S
SF
Liquid Level Glass
Combined by:
DN 185
DN 335
DN 590
LLG 185 + LLG 335
DN 740
DN 995
LLG 185 + LLG 740
DN 1145
LLG 335 + LLG 740
DN 1550
LLG 740 + LLG 740
Safety system with welding nipples
Safety system with stop valves (SVA 6 T 123)
Safety system with stop valves and acrylic glass
Important!
Where products need to be certified according
to specific certification societies or where
higher pressures are required, the relevant
information should be included at the time of
order.
ã Danfoss A/S, 05 - 2001
RD.6D.B2.02
7
Data sheet
Liquid level glasses, type LLG 185 - 1550
8
RD.6D.B2.02
ã Danfoss A/S, 05 - 2001
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