Vaisala HMT370EX User Manual

M212305EN-A

User Guide

Intrinsically Safe Humidity and Temperature

Transmitter Series

HMT370EX

PUBLISHED BY

Vaisala Oyj

Vanha Nurmijärventie 21, FI-01670 Vantaa, Finland P.O. Box 26, FI-00421 Helsinki, Finland

[phone]

Visit our Internet pages at www.vaisala.com.

© Vaisala 2021

No part of this document may be reproduced, published or publicly displayed in any form or by any means, electronic or mechanical (including photocopying), nor may its contents be modified, translated, adapted, sold or disclosed to a third party without prior written permission of the copyright holder. Translated documents and translated portions of multilingual documents are based on the original English versions. In ambiguous cases, the English versions are applicable, not the translations.

The contents of this document are subject to change without prior notice.

Local rules and regulations may vary and they shall take precedence over the information contained in this document. Vaisala makes no representations on this document’s compliance with the local

rules and regulations applicable at any given time, and hereby disclaims any and all responsibilities related thereto.

This document does not create any legally binding obligations for Vaisala towards customers or end users. All legally binding obligations and agreements are included exclusively in the applicable supply contract or the General Conditions of Sale and General Conditions of Service of Vaisala.

This product contains software developed by Vaisala or third parties. Use of the software is governed by license terms and conditions included in the applicable supply contract or, in the absence of separate license terms and conditions, by the General License Conditions of Vaisala Group.

		Table of contents
Table of contents
1.	About this document.....................................................................................	7
1.1	Version information..........................................................................................	7
1.2	Related manuals................................................................................................	7
1.3	Documentation conventions............................................................................	7
1.4	Trademarks........................................................................................................	7
2.	Product overview............................................................................................	9
2.1	Introduction to HMT370EX series...................................................................	9
2.2	Basic features and options..............................................................................	9
2.3	Hazardous area safety......................................................................................	9
2.4	Available measurement parameters.............................................................	10
2.5	Display options.................................................................................................	11
2.5.1	LED states in transmitter with no display..............................................	12
2.6	Connectivity to Vaisala Insight software......................................................	12
2.7	Transmitter parts.............................................................................................	13
2.7.1	Cable gland and conduit options...........................................................	14
2.8	Using HTM370EX Series transmitters in hazardous locations...................	16
2.8.1	Guidelines for safe use in hazardous conditions..................................	17
3.	Probe options..................................................................................................	21
3.1	HMT370EX probe options overview..............................................................	21
3.1.1	HMT370EX probe accessories...............................................................	22
3.2	HMP371 fixed probe........................................................................................	23
3.3	HMP373 probe for confined spaces..............................................................	23
3.4	HMP374 probe for high pressure applications............................................	25
3.5	HMP375 probe for high temperature applications.....................................	26
3.6	HMP377 probe for high humidity applications...........................................	27
3.7	HMP378 probe for pressurized pipelines.....................................................	28
3.7.1	Attaching ball valve kit to process........................................................	30

3.7.2HMP378F probe option for measuring oil moisture and

temperature..............................................................................................

31

3.7.3HMP378H probe option for measuring fuel moisture and

	temperature..............................................................................................	31
4.	Installation.......................................................................................................	33
4.1	HMT370EX installation overview..................................................................	33
4.1.1	Installation preparations........................................................................	34
4.1.2	Probe installation overview....................................................................	35
4.1.3	HMT370EX transmitter dimensions......................................................	35
4.2	Mounting.........................................................................................................	36
4.3	Attaching cable glands and conduit fittings...............................................	37
4.4	Wiring..............................................................................................................	38
4.4.1	Wiring with galvanic isolators...............................................................	40
4.4.2	Wiring with Zener barriers......................................................................	41
4.5	Finalizing installation: closing transmitter and attaching grounding......	42
4.6	Optional: testing analog output level with a multimeter..........................	43

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5.	HMT370 local display interface..............................................................	46
5.1	Local display overview..................................................................................	46
5.1.1	Local display PIN code...........................................................................	48
5.1.2	Light and dark display themes..............................................................	49
5.1.3	Sleep mode..............................................................................................	49
5.2	HMT370EX display main menu.....................................................................	50
5.3	Settings menu.................................................................................................	50
5.3.1	Display menu............................................................................................	51
5.3.2	Analog outputs menu ............................................................................	52
5.3.3	Measurement settings menu..................................................................	52
5.4	Calibration menu............................................................................................	53
5.5	Status menu....................................................................................................	53
5.6	Maintenance menu.........................................................................................	54
6.	Operating with Insight PC software......................................................	55
6.1	Vaisala Insight PC software...........................................................................	55
6.1.1	Basic and Advanced user modes..........................................................	55
6.2	Connecting to Insight PC software...............................................................	55
6.2.1	Installing driver for the USB service cable...........................................	57
6.3	Insight main view with transmitter...............................................................	59
6.4	Insight main view with probe.......................................................................	60
7.	Analog output configuration....................................................................	61
7.1	Analog output configuration overview.........................................................	61
7.2	Configuring analog outputs with Insight.....................................................	62
7.3	Configuring analog outputs with local display interface...........................	62
7.4	Analog output level test................................................................................	63
7.4.1	Testing analog output level with local display interface....................	63
7.4.2	Testing analog output level with Insight..............................................	64
8.	Environmental compensation and measurement settings..........	66
8.1	Environmental compensation and measurement settings overview......	66
8.2	Configuring pressure compensation............................................................	67
8.3	Configuring filtering factor............................................................................	68
8.4	Configuring calculation coefficients............................................................	69
8.4.1	HMP378F calculation model with average oil coefficients................	69
8.4.2	HMP378F calculation model with oil-specific coefficients................	70
9.	Calibration and adjustment.......................................................................	71
9.1	Calibration and adjustment overview...........................................................	71
9.2	Adjusting measurements with Insight.........................................................	72
9.3	Adjusting measurements with HMT370EX local display interface...........	72
9.4	Analog output adjustment overview...........................................................	74
9.4.1	Adjusting analog output level with Insight..........................................	76
9.4.2	Adjusting analog output level with local display interface................	77

2

		Table of contents
10.	Maintenance....................................................................................................	78
10.1	Overview..........................................................................................................	78
10.1.1	Technical support....................................................................................	78
10.2	Cleaning...........................................................................................................	78
10.3	Changing probe filter.....................................................................................	78
11.	Troubleshooting............................................................................................	80
11.1	Problems and their possible solutions........................................................	80
11.2	Error messages................................................................................................	81
11.3	Restoring factory default settings................................................................	82
12.	Technical data................................................................................................	84
12.1	Specifications..................................................................................................	84
12.2	HMP371 specifications....................................................................................	88
12.3	HMP373 specifications...................................................................................	88
12.4	HMP374 specifications...................................................................................	89
12.5	HMP375 specifications..................................................................................	90
12.6	HMP377 specifications....................................................................................	91
12.7	HMP378 specifications...................................................................................	92
12.8	Spare parts and accessories..........................................................................	93
12.9	Recycling instructions....................................................................................	94
Maintenance and calibration services........................................................		99
Warranty............................................................................................................		99
Technical support............................................................................................		99
Recycling...........................................................................................................		99

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HMT370EX User Guide M212305EN-A

List of figures

Figure	1	HMT370EX transmitter display options......................................................	11
Figure	2	HMT370EX transmitter external parts.......................................................	13
Figure	3	HMT370EX transmitter internal parts........................................................	14
Figure	4	Default plugs in HMT370EX lead-throughs..............................................	15
Figure	5	HMT370EX parts overview............................................................................	17
Figure	6	Location of test points and service port...................................................	19
Figure	7	HMT370EX probe options.............................................................................	21
Figure	8	Dimensions in mm (inches)..........................................................................	23
Figure	9	Dimensions in mm (inches)..........................................................................	23
Figure	10	Left: Installation kit for duct mounting. Right:
		Installation flange. Aluminum or stainless steel.....................................	24
Figure	11	Dimensions in mm (inches)..........................................................................	25
Figure	12	HMP375 probe and stainless steel installation flange.
		Dimensions in mm (inches)..........................................................................	26
Figure	13	Dimensions in mm (inches)..........................................................................	27
Figure 14		Dimensions in mm (inches)..........................................................................	29
Figure	15	Example wall installation with HMP373 probe........................................	33
Figure	16	Duct installation example with HMP373 probe and duct
		installation kit...................................................................................................	35
Figure	17	HMT370EX transmitter dimensions...........................................................	35
Figure	18	Mounting HMT370EX directly through the transmitter body............	36
Figure	19	Wiring example using one cable................................................................	39
Figure 20		Wiring diagram with galvanic isolators...................................................	40
Figure	21	Wiring diagram with Zener barriers...........................................................	41
Figure 22		Multimeter test point overview..................................................................	44
Figure 23		HMT370EX local display examples: measurement graph
		view and main menu screen........................................................................	46
Figure 24		HMT370EX display interface buttons.......................................................	46
Figure 25		2 parameter view example...........................................................................	47
Figure 26		Graph view example.......................................................................................	47
Figure 27		Parameter list view example.......................................................................	48
Figure 28		Display PIN code button presses...............................................................	48
Figure 29		Dark (left) and light (right) display theme examples...........................	49
Figure 30		Transmitter display in sleep mode.............................................................	49
Figure	31	HMT370EX display interface main menu.................................................	50
Figure 32		Settings menu.................................................................................................	50
Figure 33		Display menu.....................................................................................................	51
Figure 34		Analog output settings.................................................................................	52
Figure 35		Calibration menu.............................................................................................	53
Figure 36		Status menu......................................................................................................	53
Figure 37		Maintenance menu.........................................................................................	54
Figure 38		Connecting to Insight: probe body and transmitter
		service port locations....................................................................................	56
Figure 39		Insight main menu and settings: transmitter view................................	59
Figure 40		Insight main menu and settings: probe view..........................................	60

4

		List of figures
Figure 41	Analog output configuration options in Insight PC software..............	61
Figure 42	Multimeter test point overview...................................................................	63
Figure 43	Filtering factor configuration in Insight PC software............................	68
Figure 44	Insight PC software calibration view example.........................................	71
Figure 45	Local display calibration menu....................................................................	71
Figure 46	Analog output level adjustment in Insight PC software......................	76
Figure 47	Humidity measurement accuracy as function of temperature..........	85
Figure 48	Temperature measurement accuracy over full range...........................	85
Figure 49	Aw measurement accuracy..........................................................................	86
Figure 50	HMT370EX transmitter dimensions...........................................................	88
Figure 51	Dimensions in mm (inches)..........................................................................	88
Figure 52	Dimensions in mm (inches).........................................................................	89
Figure 53	Dimensions in mm (inches).........................................................................	90
Figure 54	HMP375 probe and stainless steel installation flange.
	Dimensions in mm (inches)..........................................................................	91
Figure 55	Dimensions in mm (inches)..........................................................................	92
Figure 56	Dimensions in mm (inches)..........................................................................	93
Figure 57	Recyclable and non-recyclable parts in transmitters
	with no display................................................................................................	95
Figure 58	Recyclable and non-recyclable parts in transmitters
	with no display after disposing of electronics and probe...................	95
Figure 59	Recyclable and non-recyclable parts in transmitters with display...	95
Figure 60	Recyclable and non-recyclable parts in transmitters
	with display after disposing of electrical and electronic waste.........	95

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HMT370EX User Guide M212305EN-A

List of tables

Table	1	Document versions (English)...........................................................................	7
Table	2	Related manuals...................................................................................................	7
Table	3	Available measurement parameters for HMP371, HMP373,
		HMP374, HMP375, HMP377, and HMP378...................................................	10
Table	4	Available measurement parameters for HMP378F and HMP378H.......	10
Table	5	LED status indicator states..............................................................................	12
Table	6	Cable lead-through accessories.....................................................................	15
Table	7	HMT370EX series hazardous area classifications.....................................	16
Table	8	Allowed ambient temperature ranges.........................................................	18
Table	9	Intrinsically safe input parameters................................................................	19
Table 10		HMT370EX probe accessories.......................................................................	22
Table	11	HMP371 for wall mounting..............................................................................	23
Table 12		HMP373 for confined spaces..........................................................................	24
Table	13	HMP374 for high pressure...............................................................................	25
Table 14		HMP375 for high temperature.......................................................................	27
Table	15	HMP377 for high humidities...........................................................................	27
Table 16		HMP378 for pressurized pipelines................................................................	29
Table 17		HMP378F measurement parameters............................................................	31
Table 18		HMP378H measurement parameters...........................................................	32
Table 19		Measurement performance............................................................................	84
Table 20		HUMICAPâ L2 measurement performance...............................................	85
Table	21	Operating environment...................................................................................	86
Table 22		Compliance.........................................................................................................	86
Table 23		Inputs and outputs............................................................................................	87
Table 24		Mechanical specifications...............................................................................	87
Table 25		HMP371 for wall mounting..............................................................................	88
Table 26		HMP373 for confined spaces..........................................................................	88
Table 27		HMP374 for high pressure...............................................................................	89
Table 28		HMP375 for high temperature.......................................................................	90
Table 29		HMP377 for high humidities............................................................................	91
Table 30		HMP378 for pressurized pipelines................................................................	92
Table	31	Accessory availability.......................................................................................	93

6

Chapter 1 – About this document

1. About this document

1.1 Version information

Table 1 Document versions (English)

Document code	Date	Description
M212305EN-A	March 2021	This manual. First version of the document.

1.2 Related manuals

Table 2 Related manuals

Document code	Description
M212306EN	HMT370EX Multilingual Installation and Safety Guide (languages:
	English, German, French, Dutch, Spanish, Portuguese, Italian,
	Hungarian, Czech, Polish, Finnish, Estonian, Swedish, Norwegian,
	Danish)

1.3 Documentation conventions

WARNING! Warning alerts you to a serious hazard. If you do not read and follow instructions carefully at this point, there is a risk of injury or even death.

CAUTION! Caution warns you of a potential hazard. If you do not read and follow instructions carefully at this point, the product could be damaged or important data could be lost.

Note highlights important information on using the product.

1.4 Trademarks

Vaisalaâ and HUMICAPâ are registered trademarks of Vaisala Oyj.

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All other product or company names that may be mentioned in this publication are trade names, trademarks, or registered trademarks of their respective owners.

8

Chapter 2 – Product overview

2. Product overview

2.1 Introduction to HMT370EX series

Vaisala HUMICAP® Humidity and Temperature Transmitter Series HMT370EX is the ideal solution for measuring humidity in hazardous areas. Intrinsically safe and robust, HMT370EX operates safely and reliably even in the most hazardous areas, such as Zone 0. The nextgeneration HMT370EX transmitter can be used as a replacement for the long-running HMT360 transmitter series in all HMT360 applications.

HMT370EX can be installed directly in explosive areas. It can withstand continuous exposure to potentially explosive environments that contain flammable gases or dust, and requires no additional protective enclosures for operation in either gas or dust environments.

HMT370EX o‰ers several probe options for di‰erent applications. Thanks to the detachable probe module, probes can be easily replaced and removed for calibration outside the hazardous area without removing the entire transmitter.

The transmitter has 2 analog current output channels (4 – 20 mA) for connection via safety barriers. For easy-to-use access to configuration, diagnostics, and calibration and adjustment functionalities, the probe and transmitter body can be connected to Vaisala Insight PC software for configuration either together as one unit or separately.

2.2 Basic features and options

•Available measurement parameters: relative humidity (RH) and temperature (T)

•For a list of calculated measurement parameters, see Available measurement parameters (page 10).

•Ex classification: IECEx and ATEX certified for use in Zone 0 and Zone 20 environments: for full Ex classifications, see Table 7 (page 16).

•2 analog outputs (4 – 20 mA, scalable, isolated)

•Display options: graphical LCD display or non-display model

•Power supply input: 12 – 28 V

•Compatible with Vaisala Insight PC software

2.3 Hazardous area safety

CAUTION! Do not install or use HMT370EX in a hazardous area before reviewing the safety information in Using HTM370EX Series transmitters in hazardous locations (page 16).

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2.4 Available measurement parameters

Table 3 (page 10) lists the available HMT370EX measurement parameter options and their abbreviations and units for the standard probe options HMP371, HMP373, HMP374, HMP375, HMP377, and HMP378.

Table 3 Available measurement parameters for HMP371, HMP373, HMP374, HMP375, HMP377, and HMP378

Parameter	Abbreviation	Unit
Relative humidity	RH	%RH
Temperature	T	°C (°F)
Dew point temperature	Td	°C (°F)
Dew point / frost point	Td/f	°C (°F)
temperature
Absolute humidity	a	g/m3 (gr/ft3)
Mixing ratio	x	g/kg (gr/lb)
Wet-bulb temperature	Tw	°C (°F)
Water concentration	H2O	ppmv
Water vapor pressure	pw	hPa (psi)
Water vapor saturation	pws	hPa (psi)
pressure
Enthalpy	h	kJ/kg (Btu/lb)
Dew point temperature	ΔT	°C (°F)
di‰erence
Absolute humidity at NTP	aNTP	g/m3 (gr/ft3)
Water mass fraction	H2Ow	ppmw

Table 4 (page 10) lists the measurement parameter options available for the oil and fuel probe variants HMP378F and HMP378H.

Table 4 Available measurement parameters for HMP378F and HMP378H

Parameter	Abbreviation	Unit
Available for both HMP378F and HMP378H
Temperature	T	°C (°F)
Relative saturation	RS	%RS
Water activity	aw

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		Chapter 2 – Product overview
Parameter	Abbreviation	Unit
Only available for HMP378F
Water concentration in oil	H2O (oil)	ppmw
Only available for HMP378H
Water concentration in fuel	H2O (fuel)	ppmw
Saturation temperature	Ts	°C (°F)

2.5 Display options

The HMT370EX transmitter can be ordered either with a graphical LCD display, or alternatively without a display. The display options are shown in Figure 1 (page 11).

1

2

Figure 1 HMT370EX transmitter display options

1Transmitter with display: LCD display with 4-button interface

2Transmitter without display: LED status indicator

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In the display model, probe and transmitter configuration can be carried out either using the 4-button interface of the display, or by connecting the probe or transmitter to Vaisala Insight PC software. In the model without display, all configuration must be carried out with Vaisala Insight PC software.

For information on Vaisala Insight PC software, see Vaisala Insight PC software (page 55). For information on the display interface, see Local display overview (page 46).

2.5.1 LED states in transmitter with no display

In the transmitter model with no display, the status LED indicator on the front of the transmitter provides a visual indication of the transmitter's status. If the transmitter LED status indicates that notifications or error messages exist, connect to Vaisala Insight PC software to view status information and carry out any required configuration.

For instructions on connecting to Insight, see Connecting to Insight PC software (page 55). For an overview of the Insight software, see Vaisala Insight PC software (page 55).

Table 5 LED status indicator states

LED color	Meaning
Not lit	Power o‰.
Green, fast blinking	Starting up.
Green, not blinking	Power on, normal measurement.
Green, slow blinking	Notification or warning, normal measurement. Connect to Insight
	to view status information and configure.
Red	Error. Connect to Insight to view status information and
	configure.
Red and blinking	Critical error. Connect to Insight to view status information and
	configure.

2.6 Connectivity to Vaisala Insight software

The HMT370EX transmitter and HMT370EX series probes can be connected to Vaisala Insight software either together as one unit or separately with a Vaisala USB cable (see Spare parts and accessories (page 93)). With the Insight software, you can:

•Calibrate and adjust the measurement.

•Test and adjust the analog outputs.

•Configure analog output parameter selection, scaling, error, and clipping settings.

•Configure environmental compensations, measurement settings, and local display settings.

•View real-time measurements and device and status information.

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Chapter 2 – Product overview

More information

Connecting to Insight PC software (page 55)

2.7 Transmitter parts

The external parts of the transmitter are shown in Figure 2 (page 13), and the internal parts of the transmitter are shown in Figure 3 (page 14).

1

2

3

4

5

6

7

8

9

10

Figure 2 HMT370EX transmitter external parts

1Detachable probe body

2Transmitter body (for internal parts, see Figure 3 (page 14))

3Graphical LCD display (see Display options (page 11))

4Display interface buttons (see Local display overview (page 46))

5Wall pads (4 pcs)

6Retrofit mounting plate for replacing HMT360 installations (optional)

7Probe body locking wheel

8Probe head (for information on di‰erent probe options, see HMT370EX probe options overview (page 21))

9Grounding terminal

10Lead-throughs for wiring (for lead-through accessory options, see Cable gland and conduit options (page 14))

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1

2

3

4

5

2a

V mA Test Points V mA

	2b
CH1	CH2

Figure 3 HMT370EX transmitter internal parts

1Holes for mounting screws

2Screw terminals and output test points: see 2a and 2b

2a Analog output channel 1 and 2 multimeter test points for current and voltage 2b Screw terminals for wiring analog output channels 1 and 2

3Cable fastening clamps

4Transmitter grounding terminal

5Transmitter service port (M8, requires Vaisala USB cable accessory)

2.7.1 Cable gland and conduit options

The HMT370EX transmitter body has two M20x1.5 lead-throughs that can be fitted with cable glands, conduit fittings, and plugs, as required by your application. By default, the transmitter comes delivered with 2 di‰erent plug types on the transmitter lead-throughs as shown in Figure 4 (page 15).

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Chapter 2 – Product overview

1 2

Figure 4 Default plugs in HMT370EX lead-throughs

1Removable plastic transport cover: must be replaced (fold sides of transport cover together and pull out)

2Metal sealing plug: can be used in final installation

The plastic transport cover (1) must always be replaced with an Ex compliant cable gland, conduit, or seal when wiring HTM370EX. The metal sealing plug (2) can be left in place and used in the final installation, if the right-hand lead-through is not used.

Cable glands, conduits, and plugs are available from Vaisala as accessories (listed in Table 6 (page 15)).

Table 6 Cable lead-through accessories

	Accessory	Vaisala item code
	Cable gland M20 x 1.5 for Ø 5 … 11 mm cable	265207SP
	Cable gland M20 x 1.5 for Ø 10 … 14 mm cable	265208SP
	Conduit fitting M16	265243SP
	Conduit fitting NPT1/2"	265240SP
	Dummy plug (Ex, 2 pcs)	254931SP

CAUTION! If you use lead-through accessories not ordered from Vaisala, note the following requirements:

•The cable glands and cables used for wiring the device must not impair the Ex protection.

•Unused lead-throughs must be sealed using Ex compliant plugs.

•The glands and plugs must be water and dust tight (minimum IP rating: IP54).

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2.8 Using HTM370EX Series transmitters in hazardous locations

WARNING! Protected installation using galvanic isolators or Zener barriers is mandatory in a hazardous environment.

In hazardous environments, always connect the transmitters via galvanic isolators or Zener barriers. A galvanic isolator or Zener barrier must also be used when the transmitter and probe body are in a safe area, but the probe head is installed in a hazardous environment. For wiring information, see the galvanic isolator and Zener barrier wiring diagrams included in this document.

HMT370EX does not include a galvanic isolator or a Zener barrier. They can be ordered as optional accessories from Vaisala.

WARNING! HMT370EX series transmitters have been designed for use in hazardous locations as specified by the product classification. The personnel installing, using, or maintaining HMT370EX transmitters are responsible for determining the appropriate protection concept for the specific application HMT370EX is used in, and that the hazardous area classification of the device meets the requirements of the application.

WARNING! If the equipment is used in a manner not specified by Vaisala, the protection provided by the equipment may be impaired.

HMT370EX series transmitters are certified for use in hazardous areas as defined by the following classifications:

Table 7 HMT370EX series hazardous area classifications

Certification	HMT370EX classification
IECEx 1) / ATEX 2)	II 1 G Ex ia IIC T4 Ga
	II 1 D Ex ia IIIC T200 85 °C Da
	-40 °C ≤ Tamb ≤ +60 °C

1)International certification

2)EU certification

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Chapter 2 – Product overview

CAUTION! The personnel installing, operating, and maintaining HMT370EX transmitters must have the required competencies for working in the hazardous location, as defined by the applicable standards.

For information on the standards that apply to using HMT370EX based on the classification of the device, see HMT370EX certification documentation and the declarations of conformity related to HMT370EX at www.vaisala.com/declarationofconformity.

2.8.1 Guidelines for safe use in hazardous conditions

HMT370EX Series parts overview
		HMT370EX
1	1a	2	3

M20x1.5 M20x1.5

Figure 5 HMT370EX parts overview

HMT370EX Series transmitters consist of 3 main parts: the transmitter body, a detachable probe body, and a probe head attached to the probe body, either directly or using a cable. Figure 5 (page 17) shows the main parts.

1Probe heads (for variant descriptions, see HMT370EX User Guide) 1a Probe head filters

2Probe body

3Transmitter body

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The di‰erent probe head variants are designed for a range of applications, and have their own specifications. Ensure that the transmitter body, probe body, and probe head are each placed in an environment that matches the specification of the part. For allowed ambient temperature ranges, see Table 8 (page 18).

Table 8 Allowed ambient temperature ranges

Equipment part	Allowed ambient temperature range
Transmitter body	-40 °C … +60 °C (-40 … +140 °F)
Probe body	-40 °C … +60 °C (-40 … +140 °F)
Probe heads HMP374, HMP375, HMP377, and	Temperature class T4:
HMP378	-70 °C … +120 °C (-94 … +248 °F)
	Temperature class T3:
	-70 °C … +180 °C (-94 … +356 °F)
Probe head HMP371	Temperature class T4:
	-40 °C … +60 °C (-40 … +140 °F)
Probe head HMP373	Temperature class T4:
	Rubber cable version:
	-40 °C … +80 °C (-40 … +176 °F)
	FEP cable version:
	-40 °C … +120 °C (-40 … +248 °F)

2.8.1.1 Specific conditions of use

CAUTION! With the installation of the equipment in Zone 0 Group II area it has to be ensured that sparks due to impact or friction do not occur.

Wiring requirements

•The cable glands and cables used for wiring the device must not impair the Ex protection.

•Unused lead-throughs must be sealed using Ex compliant plugs.

•Select a strain relief option that suits the application (either use cable glands that include strain relief or install separate clamps: see IEC 60079-14).

CAUTION! Connect only de-energized wires. Never switch on the power supply input before completing the wiring and closing the transmitter body.

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Chapter 2 – Product overview

Intrinsic safety

The overvoltage category of HMT370EX transmitters is I (non-mains equipment), and ambient pollution degree is 4, as specified in IEC 60664-1. For intrinsically safe input parameters, see Table 9 (page 19) .

Table 9  Intrinsically safe input parameters

Parameter	Value	Associated apparatus entity
		parameters
Ui	28 VDC	Uo ≤ Ui
Ii	100 mA	Io ≤ Ii
Pi	700 mW	Po ≤ Pi
Ci	12.1 nF	Co ≥ Ci + Ccable
Li	16 µH	Lo ≥ Li+ Lcable

Using analog output test points

There are test points for measuring the voltages and currents of the analog outputs, located above each screw terminal block as shown in Figure 6 (page 19). Accessing the test points on the component board requires opening the transmitter enclosure.

1

V

mA

Test Points

V

mA

CH1	!	Do not remove this cover
	CH2
	A	Service Port
		Use only in safe area

2

Figure 6 Location of test points and service port

1Multimeter test points for analog output channels 1 and 2

2Service port for PC connection

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HMT370EX User Guide

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CAUTION! The transmitter body enclosure must not be opened in an explosion hazardous area, unless a safe work permit has been issued in accordance with the standard IEC 60079-14. Either remove the transmitter from the hazardous area before opening the enclosure, or ensure that an IEC 60079-14 compliant safe work procedure has been implemented in the hazardous area.

Use an intrinsically safe multimeter that won't cause the intrinsically safe input parameters listed in Table 9 (page 19) to be exceeded when it is connected in series (current measurement) or parallel (voltage measurement) to the associated apparatus.

Using the service port

The service port (see Figure 6 (page 19)) must only be used in a safe area. Either remove the transmitter from the hazardous area or ensure that a safe work procedure has been implemented in the hazardous area. Only use the Vaisala accessory PC connection cable with the service port.

Maintenance

The probe (includes probe body and head) can be detached and replaced by the user. The probe head filter (see Figure 5 (page 17)) is also user-replaceable. For other maintenance requirements, contact Vaisala.

CAUTION! The probe can be detached and changed when HMT370EX is powered. Any other live maintenance, including changing the probe head filter, is not allowed.

The content in this chapter is maintained in the following separately tracked document:

Document ID: M212506EN	Revision: A (25 Feb 2021)

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Chapter 3 – Probe options

3. Probe options

3.1 HMT370EX probe options overview

Figure 7 (page 21) shows the di‰erent probe options available for HMT370EX series transmitters. The HMP371 fixed probe option uses a probe head that attaches directly to the probe body. In the other probe options (HMP373, HMP374, HMP375, HMP377, and HMP378), the probe head is attached to the probe body with a cable.

1		2										3						4						5	6

Figure 7 HMT370EX probe options

1HMP371 fixed probe (page 23)

2HMP373 probe for confined spaces (page 23)

3HMP374 probe for high pressure applications (page 25)

4HMP377 probe for high humidity applications (page 27)

5HMP375 probe for high temperature applications (page 26)

6HMP378 probe for pressurized pipelines (page 28)

6a HMP378 variant: HMP378F probe option for measuring oil moisture and temperature (page 31)

6b HMP378 variant: HMP378H probe option for measuring fuel moisture and temperature (page 31)

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More information

Probe installation overview (page 35)

3.1.1 HMT370EX probe accessories

Table 10 (page 22) lists the available accessories for each probe option.

Table 10 HMT370EX probe accessories

Accessory	Vaisala item code	Models
M12 Indigo USB Adapter cable	USB2	All models
accessory for connecting HMT370EX
probes to Insight
Ball valve ISO 1/2 with welding joint	BALLVALVE-1	HMP378
• Pressure range at +20 °C (+68 °F)
0 … 20 bar (0 … 290 psia) (during
installation max. 10 bar (145 psia)
Duct installation kit	210697	HMP373, HMP377
Mounting flange	210696	HMP375
Cable gland M20 x 1.5 with split seal	HMP247CG	HMP373, HMP375, HMP377
Fitting body M22 x 1.5	17223SP	HMP374
Fitting body NPT1/2	17225SP	HMP374
Fitting body ISO1/2 solid structure	DRW212076SP	HMP378
Fitting body NPT1/2 solid structure	212810SP	HMP378
Swagelok fitting for 12 mm probe, 1/2"	SWG12NPT12	HMP377
NPT thread
Swagelok fitting for 12 mm probe, 3/8"	SWG12ISO38	HMP377
ISO thread
Swagelok fitting for 12 mm probe, 1/2"	SWG12ISO12	HMP377
ISO thread
Thread adapter ISO 1/2" to NPT 1/2"	210662SP	All models
Manual press	HM36854SP	HMP378/F/H

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Chapter 3 – Probe options

3.2 HMP371 fixed probe

Dimensions

The HMP371 fixed probe option has a probe head that attaches directly on the probe body, making it suitable for wall mounting applications.

127 [5]

<![if ! IE]> <![endif]>55.5 [2.19]	<![if ! IE]> <![endif]>53 [2.09]	86 (3.39)

Figure 8 Dimensions in mm (inches)

41

[1.61]

<![if ! IE]>

<![endif]>ø12 [0.47]

Specifications

Table 11 HMP371 for wall mounting

	Property	Description/value
	Temperature range	-40 … +60 °C (-40 … +140 °F)
	Probe diameter	12 mm (0.47 in)

3.3 HMP373 probe for confined spaces

Dimensions

HMP373 is a small size (ø = 12 mm) general-purpose probe that is suitable for installation into confined spaces such as ducts and channels using the duct installation kit available from Vaisala (item code 210697: see Figure 10 (page 24)).

<![if ! IE]>

<![endif]>Ø 12 (0.47)

37.5 (1.48)

98.5 (3.88)

Figure 9 Dimensions in mm (inches)

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Specifications

The HMP373 probe option has 2 operating temperature range options depending on the cable selected for the probe. The rubber cable option has a temperature range of -40 … +80 °C (-40 … +176 °F). With the Teflon cable option, the temperature range is -40 … +120 °C

(-40 … +248 °F).

Table 12 HMP373 for confined spaces

Property

Description/value

Temperature range with teflon cable

-40 … +120 °C (-40 … +248 °F)

Temperature range with rubber cable

-40 … +80 °C (-40 … +176 °F)

Probe cable length

2, 5 or 10 meters (6 ft 7 in, 16 ft 5 in, 32 ft 10 in)

Probe diameter

12 mm (0.47 in)

Installation

Duct installation kit

210697

Cable gland M20x1.5 with splitting seal

HMP247CG

Swagelok for 12mm probe, 1/2" NPT thread

SWG12NPT12

Duct installation kit 210697

75 (2.96)

50 (1.97)

adjustable

Ø12 (0.47)

flange

	duct wall	drilling 16...22
		(0.63...0.87)

Figure 10 Left: Installation kit for duct mounting. Right: Installation flange. Aluminum or stainless steel.

24

Chapter 3 – Probe options

3.4 HMP374 probe for high pressure applications

Dimensions

The HMP374 probe option is designed for measurement in pressurized spaces or vacuum chambers.

<![if ! IE]> <![endif]>ø12 (0.47)	<![if ! IE]> <![endif]>M22×1.5 or	<![if ! IE]> <![endif]>NPT 1/2"
	41 (1.61)
	120 (4.72)
	170 (6.69)

Figure 11 Dimensions in mm (inches)

Specifications

Table 13 HMP374 for high pressure

	Property	Description/value
	Temperature range	-70 … +180 °C (-94 … +356 °F)
	Pressure range	0 … 10 MPa
	Probe cable length	2, 5 or 10 meters (6 ft 7 in, 16 ft 5 in, 32 ft 10 in)
	Probe diameter	12 mm (0.47 in)
	Fitting body M22x1.5	17223
	Fitting body NPT1/2	17225

CAUTION! In pressurized processes it is essential to tighten the probe very carefully when installing to prevent the loosening of the probe by the action of pressure.

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CAUTION! When HMP374 is installed in a process with a pressure di‰ering from normal atmospheric pressure, you must enter the pressure value of the process as an environmental compensation in order to receive accurate measurement results. For information on entering environmental compensations with the transmitter display interface or Vaisala Insight PC software, see Environmental compensation and measurement settings overview (page 66).

3.5 HMP375 probe for high temperature applications

The HMP375 probe option is designed for measurement in high temperature environments.

Dimensions

41 (1.6)

51 (2.0)

75 (2.96)

50 (1.97)

<![if ! IE]>

<![endif]>ø13.5 (0.53)

192 (7.56)

253 (9.96)

drilling 16...22 (0.63...0.87)

Figure 12 HMP375 probe and stainless steel installation flange. Dimensions in mm (inches).

26

	Chapter 3 – Probe options
Specifications
Table 14 HMP375 for high temperature
Property	Description/value
Temperature range	-70 … +180 °C (-94 … +356 °F)
Probe cable length	2, 5 or 10 meters (6 ft 7 in, 16 ft 5 in, 32 ft 10 in)
Probe diameter	13.5 mm (0.53 in)
Installation
Mounting flange	210696
Cable gland M20x1.5 with splitting seal	HMP247CG

3.6 HMP377 probe for high humidity applications

The HMP377 probe option is constructed to be installed in environments with high humidities. The same duct installation kit that is used with HMP373 can be used with HMP377: see Figure 10 (page 24).

Dimensions

<![if ! IE]> <![endif]>ø 12 (0.47)	<![if ! IE]> <![endif]>M9×1
	37.5 (1.48)

79.5(3.13)

99.5(3.92)

Figure 13 Dimensions in mm (inches)

Specifications

Table 15 HMP377 for high humidities

	Property	Description/value
	Temperature range	-70 … +180 °C (-94 … +356 °F)
	Probe cable length	2, 5 or 10 meters (6 ft 7 in, 16 ft 5 in, 32 ft 10 in)
	Probe diameter	12 mm (0.47 in)

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HMT370EX User Guide	M212305EN-A
Property	Description/value
Installation
Duct installation kit	210697
Cable gland M20x1.5 with splitting seal	HMP247CG
Swagelok for 12 mm probe, 3/8" ISO thread	SWG12ISO38
Swagelok for 12 mm probe, 1/2" NPT thread	SWG12NPT12

3.7 HMP378 probe for pressurized pipelines

The HMP378 probe option is especially suitable for measurements inside pipelines. Due to its sliding fit (available probe lengths: 226 mm and 448 mm (8.90 in/17.6 in)), HMP378 is easy to install into and remove from a pressurized process. A ball valve kit (Vaisala item code:

BALLVALVE-1) is available for connecting the probe to a pressurized process or pipeline: see Attaching ball valve kit to process (page 30).

HMP378F and HMP378H probe variants for measuring oil and fuel moisture

The HMP378F and HMP378H probe options are variants of the standard HMP378, designed for measurements in oil (HMP378F) and fuel (HMP378H). They provide a specialized selection of measurement parameters (see Table 4 (page 10)) intended specifically for oil and fuel measurements. With HMP378F, oil-specific calculation coefficients can be configured into use to customize the measurement for a specific oil type: see Configuring calculation coefficients (page 69).

For more information on HMP378F, see HMP378F probe option for measuring oil moisture and temperature (page 31).

For more information on HMP378H, see HMP378H probe option for measuring fuel moisture and temperature (page 31).

28