Process Datasheet Guide: How to Write One That Doesn’t Get Kicked Back by the Vendor

You send a datasheet to a pump vendor. Two days later, it comes back with 14 questions. You answer them. It comes back again — this time with a different set of questions. Three weeks later, you’re still clarifying NPSH margins and the project deadline is blown. The problem isn’t the vendor. It’s the datasheet.

A process datasheet is the single most important document you hand off from engineering to procurement. Get it right, and the vendor delivers what you need. Get it wrong, and you own the consequences — a pump that cavitates, a heat exchanger that’s undersized, a control valve that chokes at 60% open.

After filling out hundreds of these across environmental plants and lithium battery factories, here’s what actually matters.

What a Process Datasheet Actually Is

A process datasheet is not a data dump. It’s a contract. It says: “This is what I need. You, the vendor, confirm you can deliver this, or you propose an alternative with clear deviations marked.”

Every datasheet has three sections:

Process conditions — what the fluid is, what state it’s in, what you want it to become

Performance requirements — the numbers the equipment must hit

Mechanical/construction constraints — materials, connections, space, codes

The mistake most engineers make is over-specifying section 3 while under-specifying section 1. You don’t need to tell the pump vendor what impeller diameter to use. You need to tell them the flow, head, fluid properties, and let them figure out the impeller.

Pump Datasheet: The 5 Fields That Matter Most

A standard pump datasheet (API 610 or ISO 13709 format) has about 80 fields. You don’t need to fill out all of them. These five make or break the selection:

1. Flow Rate — Normal AND Rated

Never give just one number. The vendor needs:

• Normal flow: what the pump handles 90% of the time
• Rated flow: normal × 1.1 to 1.25 (this is what the pump is sized for)
• Minimum continuous flow: the lowest flow before you need a minimum flow bypass

If you only give one number, the vendor assumes rated = normal × 1.25 and sizes accordingly. But if your “normal” was already conservative, you end up with an oversized pump that runs way left on its curve.

2. NPSH Available (NPSHa)

This is the most frequently wrong field on pump datasheets. NPSHa is a SYSTEM property, not a pump property. You calculate it from:

• Liquid vapor pressure at pumping temperature
• Static head from liquid level to pump centerline
• Suction line pressure drop (including strainers, valves, fittings)
• Atmospheric pressure (for open tanks) or tank pressure (for closed vessels)

The classic mistake: using water at 20°C for a slurry at 80°C. Vapor pressure triples. NPSHa drops. Pump cavitates.

Rule of thumb: NPSHa must be ≥ NPSHr + 1 meter margin. For hydrocarbons, you can use a smaller margin (API 610 allows this). For water-like liquids near boiling point, use at least 1.5 meters.

3. Fluid Properties — All of Them

Not just “water.” Not just “slurry.” You need:

• Density (kg/m³) at pumping temperature
• Viscosity (cP) — this changes the pump curve. Viscosity correction factors from HI 9.6.7
• Solids concentration (% by weight) and particle size distribution
• pH and chloride content (for material selection)
• Presence of dissolved gases

I once saw a pump specified for “wastewater” that turned out to be pH 2 with 500 ppm chlorides. The cast iron casing lasted three months.

4. Differential Head

Total dynamic head = static head + pressure head + velocity head + friction losses.

The common errors:

• Forgetting the pressure difference between suction and discharge vessels
• Using pipe ID instead of actual ID after corrosion allowance
• Not accounting for control valve pressure drop at max flow
• Ignoring elevation differences entirely (“oh, they’re on the same floor”)

5. Driver and Utility Data

At minimum: electrical area classification (Zone 1? Zone 2? Unclassified?), available voltage, and whether you need VFD. A VFD changes everything — the vendor needs to know the turndown range and whether you’re varying speed based on flow, pressure, or level.

Heat Exchanger Datasheet: The TEMA Sheet Decoded

Heat exchangers are worse than pumps because there are more variables that interact. You change the baffle cut and it changes the shell-side heat transfer coefficient AND the pressure drop. It’s a coupled problem.

The fields vendors actually need:

• Heat duty (kW or MMkcal/h) — not “as much as possible.” A real number.
• Inlet/outlet temperatures for both sides
• Allowable pressure drop for both sides — this is a constraint, not a wish. State it clearly.
• Fouling resistances — use TEMA recommendations, not zero. Zero fouling factor means zero fouling allowance, which means the exchanger WILL foul and you WILL be cleaning it.
• Tube material and wall thickness — based on corrosion rate, not just “SS316.”

One thing that speeds up vendor response: if you’ve already checked that your duty is physically possible. A quick LMTD calculation with correction factor Ft ≥ 0.8 confirms the configuration works. Vendors appreciate an engineer who’s done the homework.

Instrument Datasheets: The Overlooked Killers

Flow meters, level transmitters, pressure transmitters — these get the least attention and cause the most commissioning problems.

Flow Meter Datasheet Must-Haves:

• Turndown requirement: need 10:1 or 50:1? The technology changes.
• Conductivity (for magnetic flow meters): minimum 5 µS/cm. Demin water won’t work with a mag meter.
• Straight run available: upstream and downstream. If you’ve only got 3D upstream for an orifice plate that needs 10D, say so — the vendor might recommend a flow conditioner.
• Pipe schedule: the meter bore needs to match the pipe ID, not the nominal size.

Level Transmitter Datasheet Must-Haves:

• Process connection: threaded, flanged, or non-contact (radar)?
• Foam/vapor: radar doesn’t like foam. Ultrasonic doesn’t like vapor. Differential pressure doesn’t care but needs wet legs.
• Temperature and pressure at the transmitter: not just in the vessel. The transmitter electronics have limits.

Control Valve Datasheet: The One That Goes Wrong Most Often

Control valves have the highest rework rate in my experience. The root cause: the process engineer specifies the valve based on line size, and the vendor sizes it based on Cv.

What you need to provide:

• Inlet pressure (P1) at max, normal, and min flow
• Pressure drop (ΔP) at max, normal, and min flow — this is where most datasheets fail. The ΔP changes with flow. At min flow, the valve might take 80% of the system pressure drop. That’s a recipe for choked flow and noise.
• Fluid state: liquid, gas, flashing, or cavitating? If flashing is possible, say so. The valve trim material changes completely.
• Noise limit: 85 dBA at 1 meter is standard. For a valve in a control room, you might allow higher. For one next to operator stations, you might want 75 dBA.

The One Thing That Saves Time

Before sending ANY datasheet to a vendor, fill it out completely — even the fields you think don’t apply. Put “N/A” if it’s truly not applicable. An empty field means “I forgot” to the vendor, and they’ll ask.

Better: use a standard template. I’ve built datasheet templates for pumps, heat exchangers, vessels, and instruments that include:

• All standard API/ISO/TEMA fields
• Unit conversion built in (you type metric, it shows US)
• Common mistakes highlighted with notes
• Vendor response columns for easy comparison

Get the Process Datasheet Pack → — 5 datasheet templates, pre-formatted with all standard fields, conversion tables, and the notes from 13 years of vendor negotiations. $29.

---

You might also find useful:

• Control Valve Sizing and Selection Guide — how to avoid the most common valve sizing mistakes
• Centrifugal Pump Selection Guide — flow, head, NPSH, and what actually matters
• Heat Exchanger Selection Guide — when to use shell-and-tube vs plate vs air-cooled

---