Used Ion Gauge Buying Guide: Granville-Phillips vs Inficon vs MKS

This guide is for: someone about to drop $5K–$15K on a used ion gauge and wants to avoid the clusterflats I’ve seen in three service bays this month.

Let’s start with a story. Last week, a client bought an “Inficon BG100” off a reseller who called it “like new.” It failed in 48 hours because the filament was arced out—a $1,200 repair. You can’t just look at the case and know. You need to know what to ask.

Why You Should Care About the Right Ion Gauge

Ion gauges are the unsung heroes of vacuum systems. A bad one means wasted runs, misdiagnosed chamber issues, or catastrophic pump failures. Used, they cost $3K–$12K depending on brand and model. But here’s the kicker: 30% of used gauges I see have hidden damage from improper shutdowns or bad calibration. You’re not just buying a sensor—you’re buying a reliability gamble.

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Granville-Phillips 275 vs. Inficon BG100: Which Holds Value?

Let’s cut through the marketing.

• Granville-Phillips 275: This thing is a tank. I’ve seen 20-year-old units still hitting 1e-10 Torr. But here’s the rub: the filament assembly is a $900 part if it’s failed. These gauges love clean environments—if your process has hydrocarbons, the collector grid gets gunked. They’re also heavy on analog outputs, so if you need USB, you’ll need a $400 interface box.
• Inficon BG100: Smaller, smarter, but fragile. The electronics board fails in ~15% of used units due to voltage spikes. If the “cold cathode” mode is cracked, you’re paying $1,500+ for a replacement. But the software integration with modern PLCs is a win—no extra drivers needed.
• MKS IPM-330: The budget pick. These are $3K–$6K used, but the ion collector wears out in 3–5 years. I always check the last calibration date. If it’s more than 18 months old, budget $800 for a recal. They’re also picky about power stability—if your facility has brownouts, this gauge will lie to you.

Bottom line: GP = durability, Inficon = features, MKS = cost. Pick based on your process, not the logo.

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What to Inspect Before You Buy (And What to Ask)

I’ve seen buyers waste $5K on a gauge that couldn’t measure past 1e-6 Torr. Here’s what to do:

1. Filament test: Ask for a hot filament video. If it glows unevenly or flickers, the coating is gone.
2. Calibration history: Demand the last cert. If it’s over a year old, add 10% to your budget for recal.
3. Process compatibility: If you run reactive gases, avoid GP models without ceramic shields.
4. Software checks: For Inficon/PG, verify the driver version. Outdated firmware = no support.

Red flags: “No box,” “repaired,” or “unknown downtime.” Those phrases mean someone already had problems.

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Price Breakdown: What You’re Really Paying For

| Model | Used Price Range | Common Repair Cost | Lifespan (Typical) |
|-------|------------------|--------------------|--------------------|
| Granville-Phillips 275 | $5K–$10K | $900 (filament) | 10–15 years |
| Inficon BG100 | $6K–$12K | $1.5K (electronics) | 7–10 years |
| MKS IPM-330 | $3K–$7K | $800 (calibration) | 5–8 years |

MKS wins the “lowest entry cost” race, but GP and Inficon last longer. Always factor in your maintenance budget.

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FAQ: What Buyers Actually Ask

"used Granville-Phillips 275 price"
$5K–$10K used. Add $900–$1,200 if the filament is bad.

"Inficon BG100 reliability"
15% of used units have failed electronics. Always check the power supply.

"MKS IPM-330 calibration cost"
$600–$800 for NIST-traceable recal. Do it every 12–18 months.

"Granville-Phillips vs Inficon accuracy"
Inficon claims 2% better linearity below 1e-9 Torr. In practice, GP holds up if maintained.

"how to test used ion gauge"
Run a leak test with helium. If it can’t detect 1e-8 Torr, it’s junk.

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What To Do Next

1. Define your spec: Know your pressure range, gas type, and interface needs.
2. Get a full service report: Pay $200–$300 for a pre-purchase inspection. It’s cheaper than a repair.
3. Negotiate based on age: Subtract 5–10% per year over 5 years old.
4. Buy from a broker with a return policy: You need 30 days to test, not 3 days.

If you follow this, you’ll avoid the 70% of used gauge buyers who regret their purchase within six months.

Related reading: MKS 1179B Mass Flow Controller Guide | How to Evaluate Used Semiconductor Equipment

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Last updated: May 2026. Information on semiconductor equipment availability and pricing reflects current secondary market conditions.

Page last reviewed May 2026. Pricing and availability reflect current 2026 secondary market conditions.