Compare total installed cost, not only sensor price

Define the purchasing boundary

List the sensor, adapter, seal, cable, interface and any required configuration tool or service. Identify whether a new vessel connection or control-system change is needed. A quotation for a bare sensor should not be compared directly with a complete installed package.

Use actual operating assumptions

Estimate maintenance effort from the process rather than claiming universal savings. Include access time, cleaning, spare holdings and commissioning of replacements. If downtime is relevant, use the buyer’s own operating cost and failure experience; do not invent a payback figure from generic assumptions.

A validated existing device may have integration advantages even if its unit price is higher. A well-qualified alternative may reduce cost when replacement is straightforward.

Make tradeoffs visible

A simple comparison table can separate purchase price, one-time integration and recurring maintenance. Record uncertain items as questions instead of treating them as zero. This supports a defensible choice and reduces disagreement after the purchase order.

What to confirm for your application

• Equivalent supply boundary
• Required installation and PLC changes
• Configuration and qualification effort
• Maintenance and spare assumptions
• Commercial terms and exclusions