# What does a thermocouple or temperature gauge save on a brass furnace, and what temperature should the metal reach?

Canonical: https://senseible.earth/answers/brass-furnace-thermocouples-three-cluster-reports

In the Bureau of Energy Efficiency (BEE) Jamnagar manual, billets left at 795 degrees against 750 needed, and a gauge saves 1.8 litres of oil a tonne. The Jagadhri manual proposes 10% off wood, 24 tonnes a year. The Energy and Resources Institute (TERI) found no Balakati unit measuring melt temperature.

## Jamnagar: billet heating on furnace oil

- Operators judged billet temperature by experience. Billets were leaving at 795 degrees Celsius where pressing needed 750.
- Furnace oil 39 litres a tonne falls to 37.20 with gauges: 1.80 a tonne, 900 litres a year on 500 tonnes, rupees (Rs) 0.25 lakh at Rs 28 a litre. Cost Rs 0.20 lakh, payback 0.80 years. By my arithmetic 1.80 / 39 is 4.6% for 45 degrees of overshoot.
- Its table of recommended reheating temperatures, printed as two numbers: free cutting, forging and high tensile brass 700/750; modified forging brass 600/650; lead free brass, IS319-II, DTP, SVF, CuZn40Pb2, C-3602 and C-345 800/850. The manual does not say what the two numbers mean; I read them as a range.

## Jagadhri: wood fired annealing furnaces

- The manual ties the low efficiency of annealing furnaces to a lack of instruments for the annealing temperature. Annealing and billet reheating need 600 to 650 degrees.
- Typical unit: 5,400 kilograms of brass a day on 800 kilograms of wood, wood at Rs 4.5 a kilogram, Rs 3,600 a day, 240 tonnes a year.
- Proposed saving 10%: 24 tonnes, Rs 1.08 lakh. Thermocouples cost Rs 0.5 lakh, payback 6 months (0.46 years by my sum). For 150 units the manual gives Rs 162 lakh saved against Rs 75 lakh spent.
- The 10% is the manual's proposal. I found no measurement behind it in the pages I read, so treat it as an estimate to test on your own furnace.

## Balakati: coal pit melting

TERI's profile says brass melts at about 900 to 940 degrees, but units reported melting at about 1,100 to 1,200, and none of them had instruments to measure it or monitored melt temperature. It says a temperature indicator must become an integral part of the furnace system. It gives no saving for it. Its separate estimate for a better furnace is 20 to 30%.

## What the three agree on

- A furnace run by eye overshoots. Jamnagar's table has billets at 795 against 750 needed. In Balakati, units said they melt at 1,100 to 1,200 against about 900 to 940, though none had an instrument to check.
- The device is a small spend: Rs 0.20 and Rs 0.5 lakh in the two costed cases, paying back in 0.80 years and 6 months on the manuals' own sums (0.46 by my sum). Neither report prints a fuel bill for these furnaces, so how cheap it is against fuel is for you to check.
- Fuel saved is yours to measure: log fuel and tonnes per month before and after, with the set temperature.

## Jagadhri annealing furnace (the manual's inputs)

- 800 kilograms a day x 300 days = 240 tonnes of wood a year
- 10% = 24 tonnes x Rs 4,500 a tonne = Rs 1.08 lakh
- Payback: Rs 0.5 lakh / Rs 1.08 lakh = 0.46 years, about 5.5 months
- Carbon dioxide (CO2): wood CO2 is biogenic, so fossil CO2 does not change; report the wood tonnes cut and keep the biogenic total apart

Costs and prices are the manual's. The 10% saving is its proposal, not a measurement. Oil in Jamnagar is a fossil fuel, so its 900 litres is about 2.7 tonnes of CO2 at 2.97 kilograms a litre, an estimate.

## What Senseible does here

Self-serve, Senseible reads fuel invoices and electricity bills into monthly records; furnace temperature is custom, on request. The wood, coke or oil bought each month is on file; your temperature log and tonnes made stay with you.

- [Your carbon number for buyers and banks](https://senseible.earth/msme-carbon-number)
- [Four fixes for a Jamnagar reheating furnace](https://senseible.earth/answers/jamnagar-brass-reheating-furnace-four-fixes-compared)
- [Balakati brass: coal and charcoal counted](https://senseible.earth/answers/balakati-brass-bell-metal-cluster-coal-charcoal)
- [Kiln temperature log for a verifier](https://senseible.earth/answers/kiln-temperature-log-what-verifier-wants)

Sources: [BEE, Manual on energy conservation measures in brass cluster Jamnagar (Winrock International India)](https://sameeeksha.org/pdf/clusterprofile/Brass_cluster_Jamnagar.pdf), [BEE and Zenith Energy Services, Manual on energy conservation measures in brass and aluminium cluster, Jagadhri](https://sameeeksha.org/pdf/clusterprofile/Jagadhri_Brass_&_Aluminium_Industries.pdf), [TERI, Cluster profile: Balakati brass industries (SAMEEEKSHA)](https://sameeeksha.org/pdf/clusterprofile/balakati-brass-Odisha.pdf)

Last reviewed 2026-11-06. The BEE manuals for Jamnagar and Jagadhri print no year; TERI's Balakati profile is 2016. The temperature pairs are printed as given; the reading of them as a range is the author's.