Chromalox Circulation Heaters Selection Guide

Circulation Heaters

Selection Guidelines

Circulation

Selecting a Circulation Heater

Selecting the proper circulation heater compo­nent requires critical engineering judgement
and careful evaluation of the application. After
determining the heat requirement for a specific
heat application, the proper selection of the
flange and vessel material, heating element
sheath material, and correct watt density is
critical to achieve long heater life. The ultimate
selection of equipment is determined by the
knowledge of the process and engineering
acumen of the designer or plant engineer. Con­sult the Technical section of this catalog for
circulation heater calculations and guidelines.

Application Factors

Heater selection is influenced by the following
parameters.

1 The heated medium, viscosity, specific
heat, density and corrosive properties.

2 The presence of contaminants in the
medium.

3 The corrosion resistant properties of the
heater sheath material.

4 The sheath watt density of the heating
elements — the watts per square inch, and
the flow rate of the heated medium.

Corrosion Policy

Chromalox will not warrant any electric heater
against failure by sheath corrosion if such
failure is the result of operating conditions be­yond the control of the heater manufacturer. It
is the responsibility of the purchaser to make
the ultimate choice of sheath material based
on his knowledge of the chemical composi­tion of the corrosive solution, character of
materials entering the solution, and controls
by which he maintains the process.

5 The vessel design and material — pressure
and temperature of the fluid being heated.

Circulation Heaters — Selection Guidelines

1 2 3 4 5

Solution or

Application

Water Clean Water pH6 to pH8 (Neutral) Copper 45 - 100 Galvanized Steel
Mild Solutions Process Water and Very Weak Solutions

Corrosive &
High Viscous
Solutions

Oil Low Viscosity Oils

Air, Gases
& Steam

Weak Solutions
Demineralized, De-ionized or Pure Water

Mildly Corrosive Solutions
More Severe Corrosive Solutions
Severely Corrosive Solutions

Medium Viscosity Oils
High Viscosity Oils (Fuel Oil)

Medium Temperatures to 750°F
High Temperatures to 1400°F

Heater Type

Alkaline or Acid Content

(Est. % by Volume)

pH5 to pH9 (2 - 3%)

5 - 6%

—

5 -15%
10 - 25%
30 - 60%

—
—
—

—
—

Sheath

Material

INCOLOY
INCOLOY
INCOLOY

INCOLOY
INCOLOY
INCOLOY

Steel
Steel
Steel

INCOLOY
INCOLOY

®

®

®

®

®

®

®

®

Watt Density

2

(W/In

) Vessel Material

45 - 86
45 - 75
45 - 75

20 - 25
20 - 25
10 - 20

20 - 25
10 - 20

5 - 15

20 - 25
10 - 20

Stainless Steel
Stainless Steel
Stainless Steel

Stainless Steel
Stainless Steel
Stainless Steel

Steel
Steel
Steel

Steel
Stainless Steel

Typical Applications

Inline Heating — Where demands for heated
water or oil are nearly constant, circulation
heaters may be installed directly in the fluid
line, eliminating the need for storage tanks and
their related heat losses.

Shut Off Valve

Outlet to

Application

Inlet from

Storage Supply

Strainer

and Pump

(when used)

C-2

Pressure Relief Valve

Drain

Side Arm — Requirements of large storage

tanks can be satisfied by using a number of
circulation heaters, providing flexibility in tem­perature control and reducing power demand.

Pressure Relief Valves

Outlet

Thermostat

Bulbs

Drain

Closed-Loop Fuel Oil Heating —Require-

ments may be provided by a number of
circulation units individually adjustable to
temperature and fluid flow, reducing electrical
demand on your utility bill.

Return Line to Tank

Storage Tank

From Fuel

Oil Tank

Sump

Strainer

Pump

To Fuel

Oil Burner

Circulation

Circulation Heaters

Selection Guidelines (cont'd.)

Circulation Heaters — Selection Guidelines

Application

Clean Water Copper/Steel

Clean Water
or Oil

Corrosive &
High Viscous
Solutions

Oil
Light
Medium

Heavy Steel/Steel 3 - 120

Steam, Air & Gas INCOLOY®/

Pre-engineered Packages — Wired & Skid Mounted C-34
ASME & Custom Engineering Specifications (SDS) C-35

Heater/Vessel

Material

or Brass
Copper/Galv.

Steel
INCOLOY®/

Galvanized

INCOLOY®/
Stainless
INCOLOY®/
CPVC

Steel/Steel 3 - 120

Steel

INCOLOY®/
Stainless

kW

Rating Feature Model Page

1.5 - 3 Booster NWHJR C-13

3 - 18

6 - 500

0.5 - 40 Field Adjustable NWHSRG C-14

6 - 200

2 - 30

1.5 - 3

30 - 120

20 - 70

30 - 50

0.5 - 3.0
3 - 350
2 - 200

Scr

ew Plug

Flanged

Flanged
Reduced Watt Density
Non-Metallic Body

Flanged
Baffled

Reduced W
Baffled

Low Flow
Flanged
Flanged
Baffled

att Density

NWH C-11

NWHIS
NWHOIS
CVCHS

NWHSR
NWHO
NWHOB

NWHOR
NWHORB

GCHCIS
GCHI
GCHIS
GCHISB

Codes & Standards

ASME Certification to Sections I, III, IV and
VIII, Division 1 or PED —Chromalox is the

leader in providing ASME (American Society of
Mechanical Engineers or PED) certification for
pressure vessel applications.

Underwriters Laboratories — UL Listing
available for many circulation heaters. Consult
your Local Chromalox Sales office.

ATEX Directive — Many Chromalox products
are approved for use in explosive atmoshpe­here

Canadian Standards Association —CSA
certification available.

National Electrical Code (NEC and IEC) — All
Chromalox circulation heaters are built to allow
NEC installation requirements.

Special Features Available

Kilowatt Ratings —Large kilowatt circulation
heaters (500 kW and above) are available as
single chambers or with multiple chambers
in series. Skid mounting and integral control
panels are also available.

Vessel Construction — Chamber size available
in 10, 12, 14, 16, 18" and above for larger
kilowatt capacities.

Pressure Ratings — 150, 300, 400, 600, 900,
1,500 and 2,500 Lb. Class.

Materials — 304, 316, 321, 347 Stainless
Steel, INCONEL

®

and more.

Thermocouplescan be provided on element
sheath for overtemperature protection and/
or mounted in the outlet nozzle for process
control.

Inlet and Outlet Nozzles — Available with
flanged or threaded connections, smaller or
larger pipe sizes and different orientations.

Bafflesmounted on element bundle inside
chamber to increase fluid or gas velocity.

Terminal Standoffs in 4, 6 and 8" allow the
terminal enclosure housing and the field wir­ing connection to operate at lower tempera­tures in high temperature heaters. Standoffs
are frequently used in heat transfer and gas
heating applications.

Mounting Saddlesfor horizontally mounted
circulation heaters.

Weatherproof Insulation Jacket for outdoor
unprotected installations.

C-29
C-30
C-16

C-19
C-17
C-18

C-21
C-21

C-33
C-24
C-32
C-32

CIRCULATION

HEATERS

C-3