Hewitt Industries

Hewitt pyrometers require no power.  NEVER apply vehicle voltage to pyrometer terminals, damage beyond repair will occur.  Only the illuminating lamp requires voltage.

Instrument Installation:
The pyrometer instrument should be mounted securely to minimize vibration; flexible brackets are not advised.  Locate in best viewing position.  If lamp is removed during installation, lamp hole should be plugged or taped over to prevent dirt or metal particles from contaminating the movement.

Thermocouple Installation: 
Various threaded mounting adapters are available, i.e.1/8 NPT, 1/4 NPT, 3/8 NPT, and 1/2 NPT.  If not specified, 1/4 NPT will be supplied.

Location will vary depending on application and engine.  On turbo charged engines, whenever possible, thermocouple should be installed in manifold before the turbocharger - this will give the highest temperature indication and the best response time.  Hewitt thermocouples are designed to tolerate this location safely and carry a lifetime warranty.  If mounting pre-turbo is not possible, a lower temperature of 150-200F will result when mounting after the turbo.

For non-turbo engines, thermocouple may be installed in the manifold before or just after the exhaust pipe flange, as is convenient.

Connecting terminals have staggered lengths to insure correct polarity, plus color match to extension wire. A plastic heat shrinkable tube is supplied with the thermocouple and should be slid over the terminals after connection is made with the extension wire and shrunk in place with heat for insulation purpose.

Extension Wire:
Standard available lengths are 7 ft. minimum, 12 ft., and 14 ft. maximum.  If longer length is required, 2-conductor 18 gauge wire may be added between extension wire and instrument, also available color coded from Hewitt.  When installing the extension wire, care should be taken to stay clear of exhaust system and chafing areas.  Secure with tie wraps, etc. to eliminate wire movement.  Terminal connections to pyrometer are designed to insure correct polarity.