Nittan NHD-G series User manual

Brand: Nittan

Model: NHD-G series

Type: User manual

Ref No:

DATE:

PAGE: ISSUE:

NISM/NHD/03

NHD-G SERIES

HEAT DETECTOR

INSTRUCTION MANUAL

MARCH 2001

OF 03

CONTENTS

Section 1 - Introduction - Page 1

Section 2 - Operation - Page 1

Section 3 - Detector Models - Page 2

Section 4 - Base Models - Page 2

Section 5 - Installation - Page 2

Section 6 - Wiring - Page 2

Section 7 - Maintenance &

Cleaning - Page 3

Section 8 - Specification - Page 4

SECTION 9 - EMC - Page 4

Section 10 - DIMENSIONS - Page 4

Section 11 - Accessories - Page 5

Section 12 - Response

Characteristics - Page 5

SECTION 1 - INTRODUCTION

The NHD-G range of attractively styled, fast re-

sponse, low profile heat detectors.

They have been designed, in most cases, to replace

our 2SA-70T-LS, TCA-70-LS AND TCA-60-LS

Features:

* Low profile, stylish appearance

* Four different response grades

* Non-polarised terminals

* Head removal signal facility

* Low monitoring current

* Integral LED alarm indicator

* Remote indicator output

* Easy maintenance

SECTION 2 - OPERATION

The NHD-G range of heat detectors are non mechani-

cal and use a thermistor of low thermal mass as the

sensing element giving a fast response. Although

these detectors operate on a fixed temperature

threshold only, their fast response makes them

generally suitable for use where rate-of-rise detectors

would be used.

Fig. 1. Block Diagram of NHD-G Detector Circuit

RECTIFIER

AND

FILTER

OPERATION

INDICATOR

SWITCHING

UNIT

VOLTAGE

STABILISER

P+

CII

SENSING

THERMISTOR

INTERNAL

REFER-

ENCE

COMPARITOR

UNIT

FIG. 1

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NHD-G SERIES

HEAT DETECTOR

INSTRUCTION MANUAL

MARCH 2001

OF 03

SECTION 3 - DETECTOR MODELS

The NHD-G range of heat detectors are available in

four versions.

i) NHD-G1 (58 deg. C) with 4 terminals. BS 5445 /

EN54 Grade 1. (Part 5)

ii) NHD-G2 (66 deg. C) with 4 terminals. BS 5445 /

EN54 Grade 2. (Part 5)

iii) NHD-G3 (74 deg. C) with 4 terminals. BS 5445 /

EN54 Grade 3. (Part 5)

iv) NHD-GH1 (80 deg.C)with 4 terminals. BS 5445 /

EN54 Range 1. (Part 8)

These versions have three terminals for connection

onto the two wire zone circuit. The remaining

terminal(P+) provides a switched current sink function

which operates when the detector goes into alarm

condition, suitable for the operation of auxilliary func-

tion such as a remote indicator.

SECTION 4 - BASE MODELS

A variety of bases are available for use with the NHD-G

detectors. It is important to use the correct base for

each application. The regularly used base models are:

i) RB-3 Base for standard use with NHD-G series heat

detector when auxiliary output not used.

ii) RB-3R Base having series resistor fitted, for use

with NHD-G 4T detector when auxiliary function not

used. Series resistor increases overall resistance of

detector/base. This should not be used to provide a

volt drop for powering a remote indicator if the control

panel needs to see the series resistor in order to

distinguish between a short circuit fault and a fire alarm

condition. This is because the presence of a short

circuit fault in the wiring to the remote indicator will

effectively short out the resistor.Three standard resistor

values are available: 220 ohm, 470 ohm and 680 ohm.

iii) RB-6 Base having 6 terminals, for use with the

NHD-G 4T detector when auxiliary output is required.

This base is normally used when a remote indicator is

required. If the control panel needs to see a higher

resistance than the detector alone provides, in order to

distinguish between a short circuit fault and a fire

alarm, then a series resistor will need to be incorpo-

rated in this base.

iv) Other bases including those that provide continuity

of the zone wiring in the event of a detector head

removal, four-wire bases etc. Refer to wiring instruc-

tions for those bases for details.

RB-6 base

RB-3 base

E.O.L

P+

Max. current through

P+= : 100 mA (total)

R.I.L

If +ve supply derived from L,

then RIL must be LED type

Max. current through

P+= : 100 mA (total)

SECTION 5 - INSTALLATION

In normal use, the NHD-G detector will be installed at

ceiling level. Pass field wiring through cable hole in

centre of base from rear of base. Offer up and affix

base to the ceiling or conduit fitting with screws via the

base mounting holes. Consider visibility and orienta-

tion of detector integral alarm indicator when mounting

base. Connect field wiring to base terminals as

detailed in below section 'Wiring', making sure that

wiring will not obstruct fitting of detector head. Fit

detector head by inserting into base and turning

clockwise until notch in detector rim aligns with base

locking screw.

SECTION 6 - WIRING

Connections are made to the detector base. The

connections used depend on the type of base and the

functions required. See Section 4 Base Models, to

identify the required type of base and functions sup-

ported. See below Figures 2,3, & 4 for wiring to the

detector's base:-

E.O.L

FIG. 2

FIG. 3

FIG. 4

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NHD-G SERIES

HEAT DETECTOR

INSTRUCTION MANUAL

MARCH 2001

OF 03

SECTION 7 - MAINTENANCE AND CLEANING

The NHD-G detector is a high quality product engineered

for reliability and to obtain optimum performance,

periodic maintenance is required. If proper preventative

maintenance is not carried out, there is a likelihood of

malfunction, including false alarms. Servicing of the

system should be carried out in accordance with BS

5839 Part 1, Fire Detection and Alarm Systems for

Buildings: Code of Practice for System Design, Installa-

tion and Servicing.

The maintenance procedures described below, should

be conducted with the

following frequency:

One month after installation: Routine Inspection

and every 3 months

Every 6 months: Operational Test

Every 12 months: Functional Test and

depending on

ambient conditions,

Cleaning

Routine Inspection

i) Ensure that the detector head is secure and undam-

aged.

ii) Check that the thermistor entry apertures are in no

way obstructed.

iii) Ensure that the surface of the detectors outer cover

is clean. If there are deposits due to the presence of oil

vapour, dust etc, then the detector should be cleaned in

accordance with the cleaning instructions detailed later

in this manual. It may be advisable to ensure that such

cleaning is conducted regularly in future.

iv) Ensure that no equipment which may generate

excessive heat, has been installed in the vicinity of the

detector since the last routine inspection. If such

equipment has been installed, then you should notify

the Safety Officer or other competent authority that its

presence may cause false alarms.

Operational Test

The purpose of the Operational Test is to confirm the

detectors correct operation in response to a heat condi-

tion.

i) Take any necessary precautions at the control panel

to limit the sounding of the alarms.

ii) Test the detector with heat from a warm air gun

designed for heat detector testing or a similar device

such as a hair dryer. Check that the detector gives an

alarm condition within 10-20 seconds depending upon

the detector grade and the applied air temperature.

Check that the LED indicator on the detector illumi-

nates.

N.B Hot air blowers sold for paint stipping, soldering

pipes etc, generate sufficient heat to damage the

detector and should not be used for testing heat

detectors.

iii) After the detector has given the alarm condition,

reset thedetector from the control. It may be necessary

to allow some short time to elapse before resetting the

detector to allow any residual heat from the test, to

disperse.

iv) Before proceeding to the next detector, ensure that

the detector just tested, does not reoperate due to the

presence of residual heat.

Functional Test

The Functional Test checks the detectors operation.

The Functional Test can only be carried out with the

NID-ET3 Electronic Tester with suitable adapter. How-

ever, these detectors may, be returned to our factory for

Functional Testing.

Details of the Functional Test method are given in the

Instruction Manual for NID-ET3, ref. NISM/ET35/01A.

Cleaning

i) Remove the heat detector from its base.

ii) Using a soft lint-free cloth, moistened with alcohol

for sticky deposites, to clean the plastic cover.

iii) Using a soft bristle brush carefully brush between

the vanes and thermistor in alinear motion away from the

plastic cover.

iv) Ensure that no debris is left on or around the ther-

mistor once cleaning is complete.

v) When replacing the outer cover, make sure that the

led indicator locates properly in the hole in the outer

cover before pushing the cover home otherwise the led

will become damaged.

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HEAT DETECTOR

INSTRUCTION MANUAL

MARCH 2001

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Ultrasonic Cleaning

This method may be used to good effect for the re-

moval of contamination from the outer cover only.

However, care must be taken in selection of the solvent

so as not to cause damage to the plastic. The solvent

supplier should be consulted as to its suitability.

Under no circumstances should the fully assembled

detector be cleaned without disassembly as this may

cause damage to the special treatment of specific

components within the detector (apart from the entrap-

ment of solvent in the cavities of the detector with the

resulting loss of solvent).

SECTION 8 - SPECIFICATION

Model References: NHD-G1,G2,G3 and GH1

Sensing Element

& Principle Thermistor of low thermal

mass.

Supply Voltage: 24V dc nominal (range 16 to

32V)

Voltage Ripple: 20% maximum

Alarm Voltage: 6V between L and C

terminals.

Monitoring Current: 30

amps maximum at 24V

Alarm Current: 65 milliamps maximum at 25

deg. C - see note

Charging Current: 100 milliamps maximum

(power on)

Charging Time: 20 seconds

Ambient Temperature

Range: -25 Deg.C. to +90 Deg.C..

Note: The power supply to the detector should

limit the maximum current that the detector can

draw 65mA. If the current is not limited then the

detector may be

damaged.

SECTION 9 - EMC

INSTALLATION AND ELECTROMAGNETIC COM-

PATIBILITY (EMC.)

The installation shall be in accordance with the regula-

tions either of the approval body for an approved

system, or otherwise, to the national code of practice/

regulations for the installation of the fire alarm system,

e.g. BS 5839 part 1.

ELECTROMAGNETIC COMPATIBILITY

On site where there is an unusually high level of poten-

tial electrical interference, e.g. where heavy currents

are being swithched or where high levels of R.F. are

prevalent, then care must be taken in the type and

routing of cables. Particular care should be given to

the separation of zone wiring from the cable carrying

the interference.

SECTION 10 - DIMENSIONS

63mm

23mm

120mm

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NHD-G SERIES

HEAT DETECTOR

INSTRUCTION MANUAL

MARCH 2001

OF 03

SECTION 12 - RESPONSE CHARACTERISTIC GRAPHS

SECTION - 11 ACCESSORIES

The following accessories are available for the NHD-G

detector:

NID-E4 Head Removal Tool for use with extension

rods to extract detector from ceiling.

DP-2 Detector Protector, wire cage to protect from

knocks and vandalism etc.

Variety of bases including 4-wire, line continuity etc.

Variety of remote indicators 6 v, 24 v led type.

Document No. NISM/NHD/03

Date MARCH 2001

NHD-G SERIES

CONVENTIONAL HEAT

DETECTOR

INSTRUCTION MANUAL

LPCB REF: 041a/01 (NHD-G1)

LPCB REF: 041a/02 (NHD-G2)

LPCB REF: 041a/03 (NHD-G3)

LPCB REF: 041b/01 (NHD-GH1)

NITTAN (UK) LTD.

Hipley Street,

Old Woking,

Surrey, England,

GU22 9LQ United Kingdom

Tel: +44 (0) 1483 769555

Fax: +44 (0) 1483 756686

Web Site: www.nittan.co.uk

e-mail: [email protected]

Quality System Certificate No. 041

Assessed to BS EN ISO 9002

Nittan NHD-G series User manual

Brand: Nittan

Model: NHD-G series

Type: User manual

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