RS N-204234 User manual

TO Order
PARTS
Call R&S Cryo
629 Grove St
Manteno IL 60950
815-468-6115
Or Fax [phone]
www.RSCryo.com
Manual # -204781
Rev. 04/08/20
SERVICE & INSTALLATION MANUAL
ELECTRIC VAPOR HEATER
CO2, Nitrogen, Argon
6/8KW CO2 N-204234 (old 1-949-0004)
N2, Ar N-340794
CO2 Dual N-350100
12/16/24KW
CO2 N-204235 (old 1-949-0012)
N2, Ar N-344644

ELECTRIC VAPOR HEATERS
For CO2, N2, Argon service
INDEX
Page
DESCRIPTION.......................................................................................................... 1-2
INSTALLATION ...................................................................................................... 2-4
THERMOSWITCH………………………………………………………………… 5-6
MAINTENANCE...................................................................................................... 7
OPERATION............................................................................................................. 7-8
TROUBLE SHOOTING............................................................................................ 9
PARTS LIST.............................................................................................................. 10
VAPOR HEATER SPECIFICATIONS .................................................................... 11
CAPACITY CALCULATIONS................................................................................ 12
FIGURE 1: Wiring Schematic for 6/8kW Vapor Heater..........................................
FIGURE 2: Wiring Schematic for 16/16/24 kW Vapor Heater................................
FIGURE 3: Assembly for CO2 6/8 kW Vapor Heater.............................................
FIGURE 4: Assembly for N2, Argon 6/8 kW Vapor Heater....................................
FIGURE 5: Assembly for CO2 6/8 kW Vaporizer/Vapor Heater............................
FIGURE 6: Schematic for CO2 12/16/24 kW Vapor Heater ...................................
FIGURE 7: Schematic for N2, Argon 12/16/24 kW Vapor Heater..........................

1
SERVICE & INSTALLATION MANUAL
ELECTRIC VAPOR HEATER
DESCRIPTION
Electric vapor heaters are used to warm cold gases being withdrawn from bulk storage tanks.
The system has a maximum design working pressure of 450 psig. A vapor heater is required in
commercial installations where cold gases/vapor is withdrawn from the storage tank or an
external vaporizer. The function of the vapor or trim heater is to warm cool or cold gases to a
suitable temperature for the operation of pressure reducing regulators, low temperature shut-off
systems or gas mixers and other equipment that is sensitive to extremely cold temperatures.
This design uses an exposed heating element which can not be used for oxygen or nitrous oxide
service.
The carbon dioxide models are manufactured using carbon steel heaters and shells and can
operate at temperatures down to -20F. Carbon dioxide vapor at 300 psig 0oF when expanded to
atmospheric pressure will cool down as cold as -80oF. This cold temperature can cause potential
damage or freeze-up of pressure reducing regulators and control valves unless the vapor is
properly warmed prior to reaching those devices. Typically, CO2vapor is heated to 70oto 100oF
so that the gas temperature exiting pressure reducing regulators is around 50oF.
Nitrogen and Argon vapor heaters are generally installed following the ambient vaporizer and
ahead of low temperature protective systems that protect the downstream piping from extremely
cold temperatures that could result from low ambient temperatures or an excessive consumption
rate. The Nitrogen and Argon models are manufactured from stainless steel to protect against
inadvertent contact with cold cryogenic liquid conditions.
This manual primarily describes the 6/8KW vapor heater since this is the most popular model.
The basic vapor heater consists of a vertically mounted zinc plated carbon or stainless steel
pressure vessel rated for a maximum working pressure of 450 psi. A 2 inch male pipe thread
immersion heater is used on the 6/8kW and a 3” 300# flange is used on the 12/16/24kW units.
All except the 3&4kW units are designed to operate on 240 or 480V 3 phase electric power. The
smaller 6/8kW units will produce 6kW on 240V and 8kW on 480V. They can be rewired to
operate on lower voltages and single phase, but will require some modifications. The
12/16/24kW heaters can operate on 240/480V at all three output capacities. They too can be
modified to operate on other voltages and on single phase power.
An integral control box is mounted on each heater that includes all the components necessary to
safely operate the unit. The control system includes a control transformer with primary and
secondary fuses. The installer is responsible for providing a fused disconnect device properly
sized to handle the expected electrical load. There is a bi-metallic temperature controller that
cycles the contactor on-off based upon the outlet gas temperature. There is a secondary overheat
sensor that is factor set to 150F to protect against excessive temperatures. This is a manual reset

2
device that must cool down and be manually reset the continue operation.
The vapor heater is designed to run unattended and maintain a uniform gas discharge
temperature. It will maintain a constant temperature as long as the gas flow rate is below rated
capacity. Flow rates in excess of rated capacity will cause the gas discharge temperature to
decrease in proportion to the flow.
The vapor heater is maintained in a constant warm condition and may be installed indoors ahead
of the pressure reducing manifold or low temperature protection system. Units used in Nitrogen
or Argon service may be set at temperatures as low as 0F to prevent wasting energy in cold
climates. Most low temperature protection systems are set to close at -20F temperatures.
The pressure vessels are rated for a minimum of 450 psig and are protected with an integral pop
type relief valve. The 6/8kW CO2 units are made with carbon steel that is externally zinc plated
to protect it from corrosion if mounted outside. Table I shows the specifications of all styles of
vapor heaters.
WARNING: These vapor heaters are NOT to be used in Oxygen, Hydrogen, or Nitrous
Oxide service. They contain bare heating elements in direct contact with the gas and are
NOT to be used on oxidizers or flammable materials.
INSTALLATION
Vapor heaters are typically installed adjacent to the bulk storage tank. The control enclosure on
the 6/8KW N-204(S/N 1-949-0004) and 12/24KW (S/N 1-949-0012) are fully gasketed and
suitable for outdoor installation.
The 6/8kW vapor heaters are typically installed in a vertical upright position with the electrical
enclosure at the top. The 12/16/24kW units are typically horizontal.
Carbon dioxide units should be installed immediately ahead of the pressure reducing regulator.
This insures that the cold vapor is warmed sufficiently that the cooling created by the expanding
gas will not damage the regulator or cause excessive chilling of the downstream piping.
Nitrogen and Argon units should be installed immediately ahead of the low temperature
manifold to warm the process vapor sufficiently to prevent tipping the low temperature
protection system either due to low ambient temperature (winter) or surge demands that might
cause cold gas to exit the ambient vaporizer. Installing the vapor heater too far away from the
low temperature protection may cause the low temperature system to cool at low ambient
conditions when there is little or no gas flow.
Mounting brackets are provided with the unit 6/8kW units to allow easy attachment to any
vertical wall or solid surface... The 12/16/24 kW unit is designed to bolt to the foundation in a
horizontal position. Both designs should be installed allowing sufficient room to remove and
replace a damaged heater element.
The vaporizer should be installed in an easily accessible position so that there is proper access to
the electrical enclosure. Allow a 3 ft clearance in front of the enclosure to meet NFPA 70 (NEC)

3
setback requirements. The installer must provide a fused servicing switch within line of sight.
The external shell of the vapor heater may reach temperatures in excess of
150oF. Employees should be kept away from direct contact to prevent
potential skin burns.
INSTALLATION PROCEDURE:
1. Attach the mounting brackets or legs to a suitable wall or solid surface with the electrical
enclosure at a convenient height. The heater outlet should ideally be above the heater and
should with the control box towards the top. A fused disconnect panel or circuit breaker
should be provided in close proximity to the vapor heater, as required by all local and
national electrical codes.
The electrical enclosure does not have an interlock mechanism and must not
be opened while the electrical power is on.
2. Connect the inlet and discharge vapor supply connections to the unit using appropriate
pressure and temperature rated piping. The inlet piping is closest to the heater element and
the outlet is adjacent to the temperature controller. The 6/8kW unit is best installed
vertically with the heater element facing downwards. Typical installations use type K silver
soldered copper or sch80 steel/stainless steel threaded piping. See CGA G-6.3 for further
information on piping for CO2 units. Pressure piping should meet or exceed ASME B31.3
power piping standards.
3. Insulating the discharge piping is optional depending upon ambient temperature conditions
and the distance that the warm vapor must travel before entering a climate controlled
building. Industrial gases dissipate heat readily and if the piping from the vapor heater is not
insulated, the gas farther down the pipe may be close to ambient temperature. All pressure
reducing regulators and control devices are typically installed following the vapor heater for
CO2 installations. This protects the regulators and piping from extremely low temperatures
caused by the expansion cooling. The N2 and Ar models are installed immediately ahead of
the low temperature protection device(s).
4. Connect the electrical supply through the 3/4" or 1-1/4” knockouts in the rear of the electrical
enclosure to the terminals to the contactor. The electrical supply must be properly labeled
as to voltage and must match the characteristics of the vapor heater. Generally the units
require 240/480 volt, 3-phase, 60 Hz power. See the appropriate wiring diagram for more
specific information. The unit can be operated on single-phase power up to the amperage
capacity of the contactor with special wiring for the individual heater elements. The
customer must provide a grounded 3 phase power supply with a fuse or circuit breaker
protected lockable disconnect means within visual sight of the installed heater to meet local
and national electrical codes.
5. Check the control circuit transformer wiring for the proper voltage and wire as per the
electrical diagram. Change the primary fuses as required to match the incoming voltage.
(See the wiring diagram for details) Most models come wired for 480V service.
WARNING
CAUTION

4
6. Set the temperature controller at a setting of approximately 100oF, or whatever temperature
is desired. It is recommended that for use with pressure reducing regulators that the gas
discharge temperature be a minimum of 70oto 100oF to prevent damage to diaphragms and
regulator parts. The range on the temperature controller is 0-400°F and a good starting
position on the controller is mid-range. The scale on the controller is not calibrated in an
actual temperature range (F or C)
7. Check to make sure that the overheat sensor in the bottom of the electrical enclosure has the
reset button properly depressed and set. The sensor will trip at 140oF in case of an overheat
condition, and requires a manual reset after the sensor has tripped. A time delay relay in the
lower left-hand corner of the enclosure needs to be set for approximately 2 to 4 seconds.
The relay is used to delay actuation of the electrical contactor to prevent chattering. There is
a narrow band in which the temperature controller may rapidly make and break contact
which could cause the contactor to chatter. The time delay relay should be adjusted to
prevent the chattering but not cause an excessive delay before energizing.
8. Wire the individual heater elements to the contactor as required by the proper wiring
diagram. The 6/8kW units have three individual elements with three sets of colored wires.
Each color of wires indicates one individual element. The 12/16/24kW heaters have six
individual heater elements with six sets of colored wires.

5

6

7
MAINTENANCE
Very little routine maintenance is required on the vapor heaters. They are designed to operate
independently with little maintenance required.
The units should be checked daily to make sure that it is functioning properly, and that warm gas
is exiting. The pressure relief valve on the unit should be checked a minimum of once every two
years to insure that it is properly functioning and not obstructed. The pop type relief valves may
continue to weep if ever actuated. They typically must be replaced if they fail to reseat.
The contactor should be inspected every six months for evidence of pitting or contact damage.
Service technicians should be trained in the properties of carbon dioxide and not do electrical
troubleshooting without being adequately trained.
OPERATING PROCEDURE
START-UP -- ALL VALVES CLOSED
1. Inspect all inlet and discharge piping to see that all piping is properly connected. Open the
vapor supply valve and allow the vapor heater to pressurize. Check for leaks.
2. Check the control circuit transformer and heater elements for proper wiring as per the wiring
diagram.
3. Check the electrical disconnect to make sure it is properly fused for the load required.
4. Set the temperature control switch in the middle of the range. Normal desired temperature
range is 70oto 100oF for CO2 units and >0F for Nitrogen and Argon units.
5. Energize the vapor heater. Allow the vapor heater to cycle a few times to insure that the
temperature controller, contactor, and time delaying relay are working correctly. Those
units that contain the time delay relay should be set so that there is a minimum time delay
before the contactor energizes but no so short as to cause the contactor to chatter. This is
typically between 2 to 4 seconds delay. If the contactor chatters during operation, increase
the time delay slightly.
6. Check for proper operation of the overheat sensor on those units that have them, by turning
the temperature controller up to the maximum. The vapor heater shell should warm up to
approximately 140oF and trip the overheat sensor. Reset the temperature controller for the
proper operating range and push the manual reset button. The vapor heater should then be
left energized to automatically cycle as required to deliver warm vapor.

8
Never attempt to adjust or repair the electrical controls without
disconnecting and locking out the power supply using an approved Lock-
Out Tag-Out procedure. (LOTO)
SHUT-DOWN PROCEDURE
1. Turn off the electrical supply power by opening the electrical disconnect switch. Verify that
there is no voltage potential on the controls prior to performing any electrical maintenance
or repairs.
2. Close the valve between the storage tank and the vapor heater inlet. The vapor heater maybe
left pressurized if desired.
3. Use Lock Out Tag Out (LOTO) procedures prior to opening or removing the vapor heater.
The vapor heaters can be left on idle indefinitely with no gas usage. The
heater elements will cycle off and on as required to maintain the set point
temperature inside the heater.
CAUTION
NOTE

9
VAPOR HEATER TROUBLE SHOOTING
SYMPTOM
PROBABLE CAUSE
REMEDY
Heater not
energizing
Electrical power failure.
Turn disconnect switch on.
Replace blown line fuses or circuit
breaker.
Replace blown transformer fuse(s).
Overheat sensor actuated.
Reset sensor and check temperature
switch operation.
Contactor coil burned out.
Replace defective contactor.
Temperature switch broken.
Replace switch and adjust to 70oto
100oF.
Heater elements burned.
Replace defective heaters.
Cool gas exiting
heater
Temperature switch adjusted too
low.
Readjust to 70oto 100oF; middle of
scale.
Replace defective switch.
Excessive vapor withdrawal.
Replace with a larger heater.
One or more heater elements
malfunctioning.
Check heater wiring.
Replace defective heater elements.
Low or improper voltage.
Check voltage and heater wiring.
Contactor
chattering
Time delay relay set too short.
Adjust relay to 2 - 4 second delay
or replace.
NOTE: Pre 1993 units may need to
install time delay relays for best
operation.
Contactor arcing
excessively
Contacts pitted.
Replace contactor.

10
SPARE PARTS LIST
6/8kW 340794 N2, Ar
6/8kW 204234 ( 1-949-0004) CO2350100 CO2
Description
Item No
Fig1
Stock No.
Old Part No.
Heater Element, 6/8KW (steel-CO2)
1A
204860
7-916-0017
Heater Element, 6/8KW (Stainless-N2Ar)
1B
340835
--
Temperature Controller
2
204176
1-050-0125
Relief Valve, 1/2", 450 psi
3
204213
1-016-0753
Control Box
4
205266
8-910-0024
Overheat Sensor, 140oF Manual Reset
5
205171
7-950-0012
Wiring Diagram
6
205027
7-936-0093
Contactor, 30A
7
204497
5-017-0241
Transformer Control Circuit 240/480V-120 75VA
8
204505
5-020-0104
Timer OFF Delay (set 4 seconds)
9
204905
7-919-0023
Fuse, 8/10A (120) Buss FRN
10
350113
--
Fuse, 1/2A (480) Buss FRN-R (2x)
11
350116
--
Fuse 1.5A (240) Buss FRN-R (2x)
12
350114
--
13
12/16/24 kW 344644 N2, Ar
12/16/24kW 204235 S/N (1-949-0012) CO2
Description
Item No
Fig1
Stock No.
Old Part No.
Heater Element, 12/16/24kW
1
27-131
--
Temperature Controller
2
27-084
1-050-0125
Relief Valve, 1/2", 450 psi
3
204213
1-016-0753
Control Box
4
27-045
Overheat Sensor, 140oF Manual Reset
5
N-205171
7-950-0012
Wiring Diagram
6
205028
7-936-0094
Contactor, 60A
7
570360A
5-017-0300
Transformer Control Circuit 240/480V-120 75VA
8
204505
5-020-0104
Timer OFF Delay (set 4 seconds)
9
204905
7-919-0023
Fuse, 8/10A (120) Buss FRN
10
350113
--
Fuse, 1/2A (480) Buss FRN-R (2x)
11
350116
--
Fuse, 1.5A (240) Buss FRN-R (2x)
12
350114
--

11
VAPOR HEATER SPECIFICATIONS
6/8KW
12/16/24KW
Part Number
N-204234
N-204235
Stock No.
1-949-0004
1-949-0012
Height
37"
28"
Width
15"
48"
Depth
15"
11-1/2"
Gas Inlet
1"FPT front
1-1/2"Mueller
Flange Rear
Gas Outlet
1"FPT top
1-1/2"Mueller
Flange Rear
MAWP
450 psig
450 psig
Overheat
Sensor
140oF
manual reset
140oF
manual reset
Temperature
Range
-100oto 600oF
-100oto 600oF
Electrical
Requirements
240/480V
3-phase
240/480V
3-phase
240V Electrical
Amps
14.4A
12KW
16KW
24KW
28.8A
38.5A
47.7A
480V Electrical
Amps
9.6A
12KW
16KW
24KW
14.4A
19.2A
28.8A
Delay Relay
1/2 - 10 sec
1/2 - 10 sec
Electrical
Enclosure
Nema-4
outdoor
Nema-4
outdoor

12
CO2CAPACITY CALCULATIONS
The vapor heater capacity is determined by the heating element power output, gas flow rate, and
the desired temperature differential. The following equations can be used to approximate the
vapor heater capacity for carbon dioxide.
For example, 8KW @ 480V with a 100odifferential (0oto 100oF)
6/8kW CO2 Vapor Heater 204234
TEMPERATURE RANGE
6KW 240V
8KW 480V
0oto 40oF
0oto 70oF
0oto 120oF
1,700 lbs/hr
1,025 lbs/hr
620 lbs/hr
2,280 lbs/hr
1,360 lbs/hr
830 lbs/hr
6/8kW N2, Ar Vapor Heater 340794
TEMPERATURE RANGE
6KW 240V
8KW 480V
0oto 40oF
0oto 70oF
0oto 120oF
ft3/hr
15,900 ft3/hr
ft3/hr
ft3/hr
21,100 ft3/hr
ft3/hr
12/16/24kW CO2 Vapor Heater 204235
TEMPERATURE RANGE
12KW
16KW
24KW
0oto 40oF
0oto 70oF
0oto 120oF
3,400 lbs/hr
2,054 lbs/hr
1,240 lbs/hr
4,500 lbs/hr
2,700 lbs/hr
1,650 lbs/hr
6,800 lbs/hr
4,100 lbs/hr
2,480 lbs/hr
erential][Temp.Diff
12,000x[kW]
=(lbs/hr)CAPACITY
erential][Temp.Diff
105,000x[kW]
=/hr)
ft
(CAPACITY
3
lbs/hr960=
100
12,000[8]
=(lbs/hr)CAPACITY
/hr
ft
8,400=
100
105,000[8]
=/hr)
ft
(CAPACITY
33