pH-sensitive glass bulb: pH_range 0-14 pH

Component Specifications

Definition

A pH-sensitive glass bulb is a precision electrochemical sensing element made from specially formulated glass containing metal oxides (typically lithium, sodium, or calcium oxides). This glass membrane develops a potential difference when exposed to aqueous solutions due to ion exchange between the glass surface and hydrogen ions in the solution. The bulb's electrical potential varies logarithmically with hydrogen ion concentration according to the Nernst equation, enabling accurate pH measurement across industrial applications.

Working Principle

The glass bulb operates on the ion-exchange principle where hydrogen ions from the solution interact with alkali metal ions in the glass membrane. This creates a potential difference across the glass membrane proportional to the pH difference between the internal reference solution and external test solution. The generated millivolt signal follows the Nernst equation: E = E0 + (RT/F) * ln(aH+), where E is potential, R is gas constant, T is temperature, F is Faraday constant, and aH+ is hydrogen ion activity.

Materials

Specialty glass composition: SiO2 (72-75%), Li2O (20-22%), CaO (2-3%), Cs2O (1-2%), with trace amounts of La2O3 and other rare earth oxides for enhanced chemical resistance and response characteristics. Internal reference electrode typically uses Ag/AgCl in 3M KCl solution.

Technical Parameters

Parameter	Typical range	Notes & selection driver
Slope	59.16 mV/pH at 25°C
PH Range	0-14 pH
Resistance	100-1000 MΩ
Zero Point	7.00 ± 0.02 pH
Bulb Diameter	8-12 mm
Response Time	<30 seconds to 95%
Temperature Range	-5°C to 130°C
Isopotential Point	7.00 pH
Membrane Thickness	0.1-0.5 mm

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Standards

ISO 10523, DIN 19264, ASTM E70, IEC 60746

Parent Products

This component is used in the following industrial products

pH Monitoring Sensors

Electronic sensors that continuously measure and report the pH level of chemical solutions in industrial neutralization processes.

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Engineering Analysis

Risks & Mitigation

Glass membrane fracture from mechanical shock
Chemical attack in extreme pH solutions
Reference junction clogging
Temperature coefficient errors
Asymmetric potential drift
Dehydration during storage

FMEA Triads

Trigger: Mechanical impact during installation or cleaning
Failure: Glass membrane fracture leading to complete sensor failure
Mitigation: Use protective guards, implement proper handling procedures, select bulbs with thicker membranes for harsh environments

Trigger: Exposure to strong alkaline solutions (pH >12)
Failure: Glass corrosion and sodium error, resulting in inaccurate readings
Mitigation: Use special high-pH glass formulations, limit exposure time, implement automatic retraction systems

Trigger: Dehydration during storage or maintenance
Failure: Increased response time and potential drift
Mitigation: Store in proper storage solution (3M KCl), implement hydration protocols before use, use hydration caps

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance

±0.02 pH for laboratory grade, ±0.1 pH for industrial grade at 25°C

Test Method

Three-point calibration using NIST-traceable buffer solutions, slope verification (95-102%), zero point verification (pH 7.00 ± 0.05), response time measurement, impedance testing

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation

Request current drawings, revision history, and a signed specification sheet.

Manufacturing capability

Verify equipment lists, process limits, capacity, and representative production evidence.

Inspection readiness

Confirm test methods, calibrated equipment, sampling plans, and traceable reports.

Supplier transparency

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Manufacturers of pH-sensitive glass bulb

Manufacturer profiles associated with pH-sensitive glass bulb.

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Frequently Asked Questions

What causes pH glass bulb degradation over time?

Degradation occurs due to chemical attack from strong alkaline solutions (pH >12), high temperatures (>80°C), dehydration when stored dry, mechanical abrasion, and poisoning from heavy metal ions or proteins that coat the glass surface.

How often should pH glass bulbs be calibrated?

Industrial applications require calibration every 1-4 weeks depending on usage intensity, solution characteristics, and required accuracy. Continuous monitoring systems should be calibrated at least monthly using standard buffer solutions at pH 4.01, 7.00, and 10.01.

Can pH glass bulbs measure non-aqueous solutions?

Standard pH glass bulbs are designed for aqueous solutions. Non-aqueous or low-ionic-strength solutions require special glass formulations or alternative measurement techniques due to different ion mobility and junction potential issues.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records. See the editorial policy.

Preliminary Technical Classification

This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

pH-sensitive glass bulb