Ontech 850 High-Precision Static/Dynamic Gas Dilution System

Overview

The Ontech 850 High-Precision Static/Dynamic Gas Dilution System is an engineered solution for trace-level gas standard preparation and calibration gas generation in environmental air quality monitoring laboratories and field-deployable analytical platforms. Based on the principle of gravimetrically controlled mass flow dilution and pressure-balanced static volumetric expansion, the system supports both static (batch-mode) and dynamic (continuous-flow) dilution methodologies within a single integrated architecture. It is specifically designed to meet the stringent requirements of VOC (volatile organic compound) reference gas preparation for canister-based sampling, GC-MS analysis, and online ambient air monitoring networks—fully aligned with HJ 759–2023, HJ 1012–2018, and HJ/T 194–2005 regulatory frameworks.

Key Features

• Hybrid static/dynamic operation mode: Switches seamlessly between static dilution (volumetric expansion in pressurized stainless-steel cylinders) and dynamic dilution (mass flow-controlled continuous blending) via software interface.
• Single-stage static dilution capability up to 10,000× without secondary dilution—enabling direct preparation of ppb-level standards from certified ppm-level parent gases.
• Dual independent gas pathways: Separate, isolated channels for calibration gas (standard) and sample gas prevent cross-contamination and support simultaneous or sequential operation.
• Full 316 stainless-steel fluidic path with proprietary silanized surface treatment to minimize adsorption, memory effects, and reactivity—critical for sulfur-containing compounds (e.g., H₂S, CH₃SH) per GB/T 14678–1993 and HJ 1078–2019.
• Integrated leak-check and pressure-hold validation routines compliant with HJ/T 194–2005 procedural verification requirements.
• High-accuracy dual-MFC compensation control unit ensures stable flow ratio control across wide dynamic ranges (typically 1–1000 sccm), supporting reproducible dilution ratios under varying backpressure conditions.

Sample Compatibility & Compliance

The Ontech 850 accommodates a broad spectrum of target analytes relevant to ambient and source emission monitoring, including but not limited to C₂–C₁₂ aliphatic/aromatic VOCs, halogenated hydrocarbons, oxygenates, and reactive sulfur species (e.g., methanethiol, dimethyl sulfide). Its inert gas handling architecture meets material compatibility requirements specified in HJ 759–2023 for SUMMA®-canister preconcentration workflows. The system supports calibration gas preparation for EPA TO-14A/TO-15-compliant methods and aligns with ISO 6142–1 (gas mixtures—preparation by gravimetry) principles for traceability. All operational protocols—including method storage, execution logs, and pressure/flow audit trails—are structured to support GLP-compliant documentation and 21 CFR Part 11–ready data integrity practices when integrated with validated LIMS or laboratory software environments.

Software & Data Management

The embedded Windows-based control software provides intuitive method setup, real-time parameter monitoring (inlet pressure, MFC readings, chamber temperature), and automated sequence execution. Predefined templates include common configurations for SUMMA canister spiking, dynamic linearity verification, and multi-point calibration curve generation. All method parameters, run timestamps, operator IDs, and system diagnostics are logged in encrypted CSV format with optional export to third-party chromatography data systems (CDS). Audit trail functionality records user actions, parameter changes, and calibration events—supporting internal QA/QC reviews and external regulatory inspections per HJ/T 194–2005 Section 6.3.

Applications

• Preparation of certified calibration standards for canister-based ambient VOC monitoring (e.g., national air quality networks, regional atmospheric stations).
• Dynamic dilution of stack effluent or fugitive emissions for real-time NMHC/THC analyzer calibration per HJ 1012–2018.
• Static dilution of high-concentration stock gases into low-ppb working standards for GC-MS laboratory analysis (HJ 759–2023).
• On-site generation of span gases for mobile monitoring units and boundary fence-line (fenceline) VOC detection systems.
• Head-space dilution of liquid standards (e.g., EPA TO-17 sorbent tube extracts) for quantitative transfer into gas-phase calibration matrices.

FAQ

Does the Ontech 850 support automated calibration verification against primary standards?

Yes—via integrated pressure decay testing and dual-MFC cross-validation routines that satisfy HJ/T 194–2005 Section 5.4 verification criteria.
Can it be used with SUMMA electropolished canisters for EPA Method TO-15 compliance?

Yes—the fully passivated 316SS gas path and zero-gasket design eliminate adsorption artifacts critical for reactive VOCs and sulfur compounds.
Is remote operation supported for unattended overnight dilution runs?

Yes—software supports scheduled task execution, email alerts upon completion/failure, and secure RDP-compatible remote desktop access.
What maintenance intervals are recommended for long-term accuracy?

MFC recalibration every 6 months; annual leak test verification and silanization re-treatment of internal surfaces per manufacturer service protocol.
Does the system comply with ISO/IEC 17025 documentation requirements for accredited labs?

Yes—full electronic record retention, version-controlled method files, and immutable audit logs enable traceability required under Clause 7.5.2 of ISO/IEC 17025:2017.