",70,8#(?(7+4:87,(:20+09>#,25,7(9:7,#7(382099,7
"5,*0-0*(90438389(11(9043(3+5,7(903.3897:*90438
:11,903#
#/, ",70,8 # (?(7+4:8 7,( :20+09>#,25,7(9:7,
#7(382099,7 takes accurate measurements in the harshest of
environments. The transmitter is offered in explosion-proof and
intrinsically-safe versions depending on the applications
requirements. The explosion-proof model is offered with 4 to 20
mA outputs for humidity only. The intrinsically-safe version is
offered with 4 to 20 mA output for humidity and temperature.
Both versions have an optional two line alphanumeric display to
show the current humidity and temperature.
The Series HHT humidity/temperature transmitter is excellent for
offshore HVAC applications, dust and grain applications.
%'!"#!$#"
/43, <<<+<>,70389*42
&@#'$" (= ,2(0103-4+<>,72(01*42
" #"
!,1(90;,:20+09>!(3.,0 to 100% RH.
#,25,7(9:7,!(3.,-40 to 140°F (-40 to 60°C).
**:7(*>±2% 10-90% RH, ±0.9°F at 72°F (±0.3°C at 25°C).
>89,7,808±1%.
!,5,(9()0109>±0.1% typical.
#,25,7(9:7,02098-40 to 140°F (-40 to 60°C).
"947(.,#,25,7(9:7,-40 to 176°F (-40 to 80°C).
425,38(9,+#,25,7(9:7,-40 to 140°F (-40 to 60°C).
4<,7!,6:07,2,398For intrinsically safe models HHT-IX, 9.5
to 28 VDC. For explosion-proof models HHT-EX, 16.5 to 28
VDC.
:95:9"0.3(14-20 mA, 2 channels for humidity/temperature
models (loop power on RH).
!,85438,#02,15 seconds.
1,*970*(1433,*90438Screw terminal block.
43+:09433,*90431/2 female NPT.
70-9<1% RH/year.
!",3847Capacitance polymer.
#,25,7(9:7,",3847Solid state band gap.
4:803.(9,70(1Aluminum.
0851(>Optional 2 line alpha numeric, 8 characters/line.
Temperature
display is °F/°C selectable.
0851(>!,841:9043RH: 0.1%: Temperature 0.1°F (0.1°C).
%,0./92 lb 8 oz (1134 g).
.,3*>5574;(18FM Approved to: XP-IS / I / 1 / BCD / T5 Ta
= -40°C to 60°C, DIP / II, III / T5 Ta = -40°C to 60°C; TYPE 4X,
IP66; IS / I, II, III / 1 / ABCDEFG / T4 Ta = -40°C to 60°C - 01-
001467-00; ENTITY; TYPE 4X, IP 66; I / 0 / AEx ia / IIC / T4 Ta =
-40°C to 60°C - 01-001467-00; ENTITY; TYPE 4X, IP 66, CE.
1/2 NPT
1/2 NPT
1/2 NPT
13-23/32
[
347.98]
4-15/32
[113.51]
2-23/32
[69.06]
3-29/32
[
99.22]
4-9/32
[108.74]
4+,1
#$
#$
##
#$
##
749,*9043
Explosion-Proof
Intrinsically Safe
Intrinsically Safe
Explosion-Proof
Intrinsically Safe
,8*7059043
Humidity
Humidity
Humidity/Temperature
Humidity
Humidity/Temperature
0851(>
No
No
No
Yes
Yes
%0703.0(.7(2A:20+09>31>
=5148043 744-389(11(904349,8
1. Install in accordance with any applicable national electric
code.
2. Plug unused conduit openings. Plug must engage a minimum
of 5 threads.
3. Use conduit seal within 18 inches of conduit entry.
4. Disconnect power before servicing.
5
. Control equipment voltage on hazardous side is 250 Vrms/DC
maximum.
6. Do not substitute any components. The intrinsic safety of the
sensor may be compromised.
7. Shielded cable for 4-20 mA loop is necessary to meet CE
requirements or when used in electrically noisy environments.
3909> (7(2,9,78
Vmax = 28 VDC
Imax = 100 mA
Ci = 62 nF
Li = 7.7 µH
Pi = 651 mW
IF SHIELDED CABLE IS USED FOR
4-20 mA LOOP, GROUND THIS SIDE
OF CABLE ONLY
4-20 mA
LOOP
SUPPLY
CONVERSION RESISTOR
2
50 OHMS
N
ON-HAZARDOUS SIDEHAZARDOUS SIDE
SHOWN TRANSPARENT
FOR CLARITY
%0703.0(.7(2A:20+09>(3+#,25,7(9:7,
3970380*(11>"(-,389(11(904349,8
1. Remove power from the instrument before carrying out any
servicing.
2. Use only FM approved Associated Apparatus. When installing
the Associated Apparatus, the manufacturer’s instructions
must be followed.
3. The earth terminal on the housing must be wired to a local
e
arth ground in the hazardous area.
4. Refer to FM control drawing, Dwyer number 03-001467-00.
5. For Model HHT-IT, use ONLY
Pepperl + Fuchs KFDØ-SCS-
Ex1.55 Galvanically Isolated Barriers.
IF SHIELDED CABLE IS USED
GROUND THIS SIDE OF CABLE ONLY
I.S GROUND
TEMP.
RECEIVER
4-20 mA
LOOP SUPPLY
SHOWN TRANSPARENT
FOR CLARITY
R
H
R
ECEIVER
MODEL HHT-IT
MODEL HHT-IT, RH AND TEMP.
INTRINSICALLY SAFE WIRING
EXAMPLE USING PEPPERL + FUCHS
BARRIER SYSTEM
H
AZARDOUS SIDE
N
OTE! THE PEPPERL +
F
UCH KFD0-SCS-Ex1.55
B
ARRIERS ARE
G
ALVANICALLY ISOLATED,
S
O GROUNDING IS NOT
R
EQUIRED.
N
ON-HAZARDOUS SIDE
KFD0-SCS-Ex1.55
KFD0-SCS-Ex1.55
MODEL HHT-IU
IF SHIELDED CABLE IS USED,
GROUND THIS SIDE OF CABLE ONLY
I.S GROUND
HAZARDOUS SIDE NON-HAZARDOUS SIDE
SHOWN TRANSPARENT
FOR CLARITY
4-20 mA
LOOP SUPPLY
MODEL HHT-IU, RH ONLY
INTRINSICALLY SAFE WIRING
EXAMPLE USING MTL BARRIER
SYSTEM
MTL7787+
RH
RECEIVER
$!B $!B
$!B
4<,7":551>!,6:07,2,398
The maximum DC Power Supply is 28 VDC. The minimum
required DC Power Supply required is based upon the following:
1
.Minimum DC voltage requirement of the Model HHT.
2.Total load resistance.
3.Total leadwire resistance.
4.Zener barrier voltage drop ( Model HHT-IX only).
The formula for calculating the DC Power Supply is:
VDC = VHHT + VLOAD + VLEADWIRE + VBARRIER
Where VHHT = 9.5v for Models HHT-IX and 16.5v for Models
H
HT-EX.
VLOAD = Total load resistance X 20mA
VLEADWIRE = Total leadwire resistance X 20mA
VBARRIER = 8.1v
(Typical zener barrier voltage drop for this application)
=(251,(1*:1(9,20302:2 4<,7":551>-47
4+,1#&=5148043 744-
Step 1. VHHT = Minimum voltage required by
Model HHT-EX = 16.5 v
Step 2. Calculate VLOAD. Using the industry standard
250 OHM conversion resistor, VLOAD =
250 X 20mA = 5v.
Step 3. Calculate VLEADWIRE. For this example assume
a leadwire resistance of 10 OHMS.
VLEADWIRE = 10 X 20mA = 0.2v
Step 4. VDC = VHHT + VLOAD + VLEADWIRE =
16.5 + 5 + 0.2 = 21.2v
=(251,(1*:1(9,20302:2 4<,7":551>-47
4+,1#$3970380*(11>"(-,
Step 1. VHHT = Minimum voltage required by Model HHT-
IX = 9.5 v
Step 2. Calculate VLOAD. Using the industry standard
250 OHM conversion resistor, VLOAD =
250 X 20mA = 5v.
Step 3. Calculate VLEADWIRE. For this example assume
a leadwire resistance of 10 OHMS.
VLEADWIRE = 10 X 20mA = 0.2v
Step 4. VBARRIER = 8.1v
Step 5. VDC = VHHT + VLOAD + VLEADWIRE +
VBARRIER = 9.5 + 5 + 0.2 +8.1 = 22.8v
For Model HHT-IT, follow instructions with Pepperl + Fuchs
KFDØ-SCS-Ex1.55 Barrier.
#
Upon final installation of the Series HHT Hazardous Area
Humidity / Temperature Transmitter, it is important to develop a
routine schedule for replacing the RH/Temperature Sensor P/N
A-451. The sensor should be replaced annually or sooner
depending on environmental conditions. A periodic check of
system calibration is recommended. The Series HHT is not field
serviceable and should be returned if repair is needed (field
repair should not be attempted and may void warranty). Be sure
to include a brief description of the problem plus any relevant
application notes. Contact customer service to receive a return
goods authorization number before shipping.
"##
4*(9043 Select a location where the ambient temperature is
between –40 to +140°F (-40 to +60°C)
4809043 The transmitter is not position sensitive. Units with the
optional display should be mounted for ease of viewing the
display.
(:9043 Use electrostatic discharge precautions (e.g. use of
w
rist straps) during installation and wiring to prevent equipment
damage.
Avoid locations where severe shock or vibration, excessive
moisture or corrosive fumes are present.
Do not exceed ratings of this device. Permanent damage not
covered by the warranty may result.
0851(> The temperature indicated on the display, if equipped
with the LCD option, is field selectable via a jumper located on
the circuit board just above the display. To change the jumper
position, remove the housing cover and position the jumper for
°F or °C according to Figure 4.
!,51(*,()1,!#,25,7(9:7,8,3847(3+8039,7,+-019,7
Replacement sensors are available. No calibration is required
when a new sensor is installed. To replace the sensor, remove
the sintered filter. When installing the new sensor, make sure the
4 pin male connector is aligned correctly with the female
connector. See Figure 5.
To order a replacement sensor or sintered filter, contact Dwyer
sales. The part numbers are:
Replacement 2% sensor : A-451
Replacement sintered filter: A-450
$!
CORRECT ALIGNMENT
OF SENSOR ASSEMBLY
INCORRECT ALIGNMENT
OF SENSOR ASSEMBLY
$!
%'!"#!$#"
/43, <<<+<>,70389*42
&@#'$" (= ,2(0103-4+<>,72(01*42
©Copyright 2014 Dwyer Instruments, Inc. Printed in U.S.A. 12/14 FR# 03-443603-00 Rev. 6
1. THE INTRINSIC SAFETY ENTITY CONCEPT ALLOWS THE INTERCONNECTION OF TWO FM APPROVED INTRINSICALLY SAFE
DEVICES WITH ENTITY PARAMETERS NOT SPECIFICALLY EXAMINED IN COMBINATION AS A SYSTEM WHEN:
2. EQUIPMENT CONNECTED TO THE ASSOCIATED APPARATUS MUST NOT USE OR GENERATE MORE THAN 250 Vrms OR VDC
3. DIVISION 1 HAZARDOUS (CLASSIFIED) LOCATIONS INSTALLATIONS MUST BE IN ACCORDANCE WITH THE NATIONAL ELECTRICAL CODE NFPA 70, ARTICLE 504;
4. NO REVISIONS WITHOUT PRIOR APPROVAL FROM FM RESEARCH.
5. THE ASSOCIATED APPARATUS MANUFACTURERS INSTALLATION INSTRUCTIONS MUST BE FOLLOWED WHEN INSTALLING THIS EQUIPMENT.
6. DUST TIGHT CONDUIT SEAL MUST BE USED IN CLASS II AND CLASS III ENVIRONMENTS.
FM CONTROL DRAWING
CATALOG NUMBERS:
HHT-IU AND HHT-IT
HHT SERIES
TRANSMITTER
Vmax=28VDC
Imax=100mA
Ci = 62nF
Li = 7.7 H
Pi = 651mW
HAZARDOUS (CLASSIFIED) LOCATION
INTRINSICALLY SAFE FOR:
CLASS I DIV. 1 GROUPS A, B, C, D
CLASS II DIV. 1 GROUPS E, F, G
CLASS III DIV. 1
T4 Ta = -40°C TO 60°C TYPE 4X, IP 66
OR
COM
RH
TEMPERATURE
+
-
-
3
4
1
2
G
GROUND CONNECTION
FM APPROVED
ASSOCIATED APPARATUS
3
4
1
2
G
GROUND CONNECTION
NON-HAZARDOUS LOCATION
I.S. SAFETY GROUND
OPTIONAL SHIELD
m
T4 Ta = -40°C TO 60°C TYPE 4X, IP 66
Voc OR Uo OR Vt Vmax, Isc OR Io OR It Imax, Ca OR Co Ci + Ccable, La OR Lo Li + Lcable, Po Pi
VI
IV
VI
I
V
VI
NOTICE: This drawing and the principles and elements of design embodied therein are the exclusive property of DWYER INSTRUMENTS, INC. and are not
to be communicated, disclosed, reproduced or used except as previously authorized in writing by such corporation and must not be submitted to outside
parties for examination without the written consent of said corporation.
NO. CHANGES BY/DATE
NAME
APPD
CHKD
DWN BY
DATE
STANDARD TOLERANCES UNLESS NOTED:
MICHIGAN CITY, INDIANA 46360 U.S.A.
F
R
.
N
O
.
3
ACAD2002
FINISH
MATERIAL
ALL DECIMAL DIMENSIONS ±
CD = CRITICAL DIMENSION
ALL ANGLES ±
03-001467-00
03-001467-00
0
3-001467-00
08-25-08
KAS
CAT
LRR
FM CONTROL DRAWING
HHT-IU AND HHT-IT
SCALE 1:2
1
UPDATED PER DWK 6-12-14, ECR 35480
PFA
6-23-14
1°
.005
PROBE TUBE
UP TO LINE
IS NOT
NEMA 4X
IP66
HOUSING ABOVE
THIS LINE IS
NEMA 4X IP66
CLASS I, ZONE 0, GROUPS IIC
ZONE 0 HAZARDOUS LOCATIONS MUST BE IN ACCORDANCE WITH THE NATIONAL ELECTRICAL CODE NFPA 70, ARTICLE 505. ALL INSTALLATIONS MUST BE
IN ACCORDANCE WITH ISA RP-12.6.
7. WARNING - ENCLOSURE PARTS ARE CONSTRUCTED OF ALUMINUM. ENCLOSURE MUST BE PROTECTED FROM MECHANICAL FRICTION AND IMPACT WITH
IRON/STEEL TO PREVENT IGNITION CAPABLE SPARKS.
8. SUBSTITUTION OF PARTS MAY IMPAIR INTRINSIC SAFETY. RETURN TO MANUFACTURER FOR ANY REPAIRS.
9. ADDITIONAL SUFFIX LCD (LCD DISPLAY) DOES NOT IMPAIR INTRINSIC SAFETY.
/
