Fuel oils terminology and use: About LSHS (a common residual fuel oil), which statement correctly characterises it for industrial furnace service?

Introduction:
Industrial firing applications often specify residual fuel oils by sulphur and viscosity classes. LSHS is a widely referenced term in Indian industry and examinations. The question checks accurate expansion and practical suitability for furnaces.

Given Data / Assumptions:

• LSHS is a residual/heavy fuel oil grade.
• HVFO denotes high-viscosity furnace oil grade(s).
• Metallurgical furnaces are sensitive to sulphur from a pollution and refractory/metal quality standpoint.

Concept / Approach:
LSHS literally expands to low sulphur heavy stock. Compared with generic furnace oils, its key selling point is reduced sulphur, which helps lower SOx emissions and scale or corrosion risks. Viscosity depends on exact blend/grade; LSHS need not be more viscous than oils explicitly sold as high-viscosity furnace oil (HVFO).

Step-by-Step Solution:

Verification / Alternative check:
Fuel oil purchasing specs separate sulphur content (LS vs HS) from viscosity classes (e.g., 80–380 cSt @ 50°C). LS and viscosity are independent levers; “HVFO” signals higher viscosity explicitly.

Why Other Options Are Wrong:

• (a): Not generally correct; HVFO grades are, by definition, very viscous.
• (d): Cannot be true since (a) is not broadly valid.

Common Pitfalls:
Assuming “low sulphur” automatically implies “high viscosity” or vice versa; they are specified separately.

Final Answer:
Only (b) and (c)