Key Technical Specifications

• Measurement Type: Absolute Pressure (Reference vacuum sealed)
• Full Scale Range: 100 Torr
• Accuracy: ±0.5% of Reading
• Output Signal: 0-10V DC or 4-20mA (Verify specific suffix config)
• Response Time: <10ms (Typical)
• Operating Temp: 0°C to 50°C (Sensor Head)
• Electronics Temp: 0°C to 50°C
• Connection: 1/4″ VCR or 1/4″ Swagelok (Verify fitting)
• Electrical Connector: 15-Pin D-Sub
• Power Supply: +15V DC / -15V DC (Dual Rail)
• Wetted Materials: Inconel 625 / Stainless Steel 316L
• Zero Stability: <0.1% FS / Month

 

Product Introduction

Most pressure sensors drift when the gas mix changes, but the MKS 220DD-00100D2B doesn’t care if you’re pumping nitrogen, argon, or a nasty etch gas because it measures force, not thermal conductivity. I’ve seen guys try to save money by using Pirani gauges for process control, then wonder why their recipe fails every time they change the gas flow; this capacitance manometer is the only way to get true absolute pressure regardless of what’s in the chamber. It’s the gold standard for a reason, and once you trust it, you stop second-guessing your base pressure readings.We stock this specific 100 Torr range because it’s the workhorse for roughing and transfer line monitoring in semiconductor and vacuum coating tools. The MKS 220DD-00100D2B uses a rugged Inconel diaphragm that handles thermal shocks better than ceramic alternatives, but don’t get cocky—I’ve seen techs drop a wrench on the sensor head and instantly zero out a $2,000 gauge. Treat it like a precision instrument, not a hammer. Also, verify your output signal; the “DD” in the part number usually implies a specific output configuration, but I’ve had customers receive a unit expecting 0-10V when they needed 4-20mA because they didn’t check the suffix code.

Quality SOP & Tech Pitfalls

The Lab Report:
Capacitance manometers are sensitive beasts, so we don’t just plug and play. Every MKS 220DD-00100D2B goes through:

1. Visual & Connector Check: Inspect the 15-pin D-Sub for bent pins or corrosion. Check the VCR/Swagelok fitting threads for galling or cross-threading.
2. Zero Verification: Pump the sensor head down to <10⁻³ Torr and verify the zero output is within spec. If it won’t zero, the diaphragm is likely fatigued or contaminated.
3. Span Check: Apply a known calibration pressure (e.g., 50 Torr) and verify linearity. We use a deadweight tester or NIST-traceable reference standard.
4. Leak Check: Pressurize the wetted side and monitor for internal leaks into the reference vacuum side. A slow leak here means the gauge is trash.

The Engineer’s Warning:
Never, ever apply pressure to the sensor head while it’s cold and then try to heat it up, or vice versa, without equalizing. Thermal shock can crack the diaphragm weld. I’ve seen a tech connect a hot gas line to a cold MKS 220DD-00100D2B and hear a faint pop; the gauge read zero forever after. Also, do not exceed 3x full scale (300 Torr) on the 100 Torr model. The diaphragm will permanently deform, and no amount of recalibration will fix it. One more thing: if you’re replacing an old unit, check the “D2B” suffix. MKS changes output scaling and connector pinouts with these suffixes. I once swapped a gauge and spent 4 hours debugging a “noisy signal” before realizing the pinout for ground was different on the newer revision.

 

Installation & Configuration Guide

1. Pre-Installation: ⚠️ ISOLATE THE CHAMBER. Vent the line to atmosphere before removing the old gauge. Take a photo of the 15-pin D-Sub wiring. Verify the new MKS 220DD-00100D2B has the exact same fitting type (VCR vs. Swagelok).
2. Removal: Use two wrenches on the VCR fitting; never use the gauge body as a backstop. You will crack the ceramic feedthrough or deform the housing. Label the D-Sub connector pins.
3. Installation: CRITICAL: Install a new VCR gasket. Reusing a crushed gasket is the #1 cause of virtual leaks. Hand-tighten the fitting, then torque to spec (usually 30-40 ft-lbs for 1/4″ VCR). Do not overtighten.
4. Power-On & Testing: Apply ±15V DC. Allow 15-30 minutes for thermal stabilization. Check the zero reading at chamber base pressure. If it’s >1% FS off, you may need to perform a zero adjustment (if equipped with a pot) or flag it for recalibration.

Compatible Replacement Models

• ✅ Drop-in Replacement: MKS 220DD-00100D2B (Exact match for 100 Torr, D-Sub, specific output).
• ⚠️ Software/Config Compatible: MKS 220DD-00100D2A (Same hardware, verify output scaling/pinout; may require controller config change).
• ❌ Hardware Mod Required: MKS 722B (Different form factor, different connector, requires new cabling and mounting bracket; only do this if you’re upgrading the whole system).

 

Frequently Asked Questions

Can I use this gauge for corrosive gases like Chlorine or HBr?
The standard 220DD wetted parts are Inconel 625 and SS316L, which handle most corrosives, but HBr and Chlorine at high temps can attack the welds over time. If you’re running nasty etch gases, check the MKS “Corrosion Resistant” options or consider a Gold-plated diaphragm variant. Don’t gamble with a standard gauge in a high-concentration etch chamber.My gauge reads 2 Torr at base pressure, but the ion pump says 10⁻⁶ Torr. Is it broken?
Probably not. The MKS 220DD-00100D2B has a zero offset or a leak. First, isolate the gauge and pump it down separately. If it still reads 2 Torr, it’s either contaminated or the diaphragm is stressed. If it zeros out, you have a virtual leak in your fitting or a crack in the weld. Check your VCR gasket first; 90% of the time, it’s a bad gasket.Do I need to recalibrate this every year?
MKS recommends annual calibration for critical processes, but in practice, these things are stable for 2-3 years if you don’t abuse them. If you’re running a tight recipe and your base pressure is drifting, calibrate it. If you’re just monitoring roughing lines, you can probably stretch it to 18 months. Just document it.Can I hot-swap this while the controller is on?
No. The ±15V rails are live, and disconnecting the D-Sub under load can arc the pins or spike the controller’s input. Power down the gauge supply first. It takes 30 seconds. Don’t be lazy.What does the “D2B” suffix actually mean?
It defines the output signal type, connector, and sometimes the zero adjustment feature. “DD” usually means Capacitance Manometer, “00100” is 100 Torr, and “D2B” is the specific electrical config. If you’re replacing a “D2A” with a “D2B”, verify the pinout. I’ve seen the signal and ground pins swap between revisions.Why is my output noisy?
Check your power supply. Capacitance manometers are sensitive to ripple on the ±15V rails. If you’re sharing a supply with solenoids or motors, you’re asking for trouble. Also, check the shield on your D-Sub cable; if it’s not grounded at the controller end, you’re acting as an antenna.