Most density-meter selection failures aren't about accuracy — they're about choosing the wrong principle. The most expensive high-accuracy meter in the wrong process won't run stably. This article uses reverse-elimination from 'can't use' to 'should use' across 6 standardized decision steps.
How to Choose an Industrial Online Density Meter: A 6-Step Method
Choosing an online density meter isn't just reading the accuracy number on a datasheet. This guide walks six connected decision steps across medium, installation, accuracy, and compliance to land on the right principle and model.
Steps
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Step 1: Document medium properties
Record medium name, density range (min-max), temperature range, pressure range, pH, solids fraction, presence of bubbles, scaling/crystallization tendency, corrosivity. This single table drives every downstream decision — solids / gas / scaling properties alone will eliminate over half the principles. -
Step 2: Define accuracy tier
Custody transfer → ±0.0005 g/cm³ class (Coriolis PS7200); process control → ±0.001 g/cm³ class (fork / DP / ultrasonic); trend monitoring → ±0.005 g/cm³ class (most principles). Repeatability matters more than absolute accuracy for alarms and closed-loop control — list it separately. -
Step 3: Audit installation constraints
Can the pipe be tapped / hot-worked? (No → PS7010 clamp-on) Is straight run adequate? (DP, ultrasonic, Coriolis all need ≥ 3D upstream + 2D downstream) Pipe size? (< DN50 narrows the field; > DN600 favors DP) Tank top / wall / pipe? — drives PS7300 A/B/C mounting choice. -
Step 4: Check compliance and Ex requirements
Radiometric source acceptable? (No → all non-nuclear; Yes → still prefer PS7500 Na22 exempt-activity) Hazardous zone? (Zone 1 mandates Ex) Food / pharma sanitary? (tri-clamp + 316L polished) Export approvals? (CE, ATEX, IECEx) -
Step 5: Rank the 'feasible set' by priority
After Steps 1-4 eliminate non-fits, rank what's left by: (a) field engineer familiarity; (b) spare-parts logistics; (c) Total Cost of Ownership (TCO — 5-year parts + calibration + downtime); (d) integration interface compatibility (4-20mA / HART / Modbus / Profibus). -
Step 6: Send to a Pisonics application engineer
Send your Step 1-5 spec sheet plus proposed model(s) to a Pisonics engineer for a written sizing proposal — we commit to a 2-business-day turnaround with recommended model, material options, accessories list, and price range. This step avoids the 'looks right on paper, fails on site' pattern from picking purely off datasheet specs.