Natural Gas
Composite Sampling Systems
Three turnkey composite sampling configurations — designed, manufactured, built, and tested at Welker to API 14.1 standards for any gas stream, any site condition.
- API 14.1 Compliant
- GPA 2166
- ISO 9001:2015 Certified
- Welker Made™
- Since 1954
Turnkey Sampling Solutions
The Right Sample. Every Time.
A representative natural gas sample is the foundation of accurate custody transfer measurement and regulatory compliance. Welker has been engineering the equipment that makes that possible since 1954 — from the probe into the pipeline to the cylinder in the laboratory.
API 14.1 Compliant — All Configurations
Every Welker sampling system meets or exceeds API Manual of Petroleum Measurement Standards Chapter 14.1.
Fresh Sample System™ Technology
Welker's patented sample path auto-purges before every grab — ensuring a fresh, uncontaminated sample each cycle.
Vanishing Chamber™ — Zero Sample Loss
The GSS-4PM's positive-displacement collection cup captures the entire sample slug with no carryover or loss.
Heated Enclosure for Any Climate
Cold climates and near-dew-point gas streams require thermostatically controlled heating — Welker builds it all in-house.
Designed & Built in Sugar Land, TX
Every component — sampler, cylinder, enclosure — engineered, manufactured, and tested under one roof since 1954.
How It Works
From Pipeline to Laboratory in Four Steps
Sample Extraction
A Welker probe extends into the center third of the pipeline, drawing a representative sample from the flowing gas stream at the correct velocity and pressure conditions for your application.
Proportional Grab Sampling
The sampler actuates in proportion to pipeline flow — collecting precisely timed sample grabs that composite into a representative average over the measurement period, automatically and unattended.
Transfer to Sample Cylinder
Each grab is delivered to the sample cylinder. The CP-2 Constant Pressure Cylinder maintains pipeline pressure in transit — preventing phase change and liquid dropout for wet or rich gas streams.
Laboratory Analysis
The sealed cylinder is transported to the laboratory for gas chromatograph analysis — producing a BTU and composition report for custody transfer billing and regulatory compliance documentation.
Heated Enclosure (If Required)
In cold climates or for gas at its hydrocarbon dew point, a thermostatically controlled heated enclosure protects the sampler and cylinder from freezing and liquid dropout throughout the sample period.
Controller & Monitoring
Welker controllers — from the simple 4P Frequency Controller to a fully integrated PLC — ensure the sampler collects at exactly the right rate to produce an accurate, representative composite sample.
Find Your Natural Gas Sampling System
Answer three questions about your application and we'll guide you to a solution.
1. What best describes your natural gas stream?
2. What is your installation environment?
3. Which sample cylinder type do you require?
- API 14.1 — Composite Sampling of Natural Gas
- GPA 2166 — Obtaining Natural Gas Samples
- ISO 9001:2015 Certified Manufacturer
- DOT 3E Cylinder Certified
- UL Listed Controllers Available
System Configurations
Three Complete Sampling Systems
Every configuration is a turnkey assembly — sampler, cylinder, and accessories — designed, manufactured, built, and tested at Welker's Sugar Land, TX facility to API 14.1 standards.
Essentials™ Gas Sampler
with SC Cylinder or CP-2 Cylinder
Welker's most compact and cost-effective composite sampling solution. The Essentials™ features the Fresh Sample System™, which purges the sample chamber before every grab — delivering a representative sample each cycle with no electronics and minimal moving parts.
Key Features
- Fresh Sample System™ — auto-purge before every cycle
- API 14.1 compliant flow-through sample path
- Pneumatically actuated — no external power required
- Ideal for remote and unmanned installations
- Low maintenance, field-proven construction
Compatible Cylinders
SC Single Cavity
CP-2 Constant Pressure
Compatible Cylinders
Clean, dry gas
Single-phase streams
Remote / unmanned sites
Budget-sensitive projects
Moderate flow rates
GSS-4 Composite Sampler
with SC Cylinder or CP-2 Cylinder
The Welker GSS-4 delivers decades of proven performance in representative composite gas sampling. The Vanishing Chamber™ collection cup uses positive displacement to capture the entire sample slug — eliminating carryover and ensuring sample integrity for wet or dry, clean or dirty gas streams.
Key Features
- Vanishing Chamber™ — positive displacement, zero sample loss
- Self-purging design for fresh, representative samples
- Probe-mounted, fully self-contained assembly
- Wet & dry gas capable with optional LE-2SSKO liquid eliminator
- Compatible with PLC, 4P Frequency Controller, or 6Tc battery controller
- Online maintenance without full depressurization
Compatible Cylinders
SC Single Cavity
CP-2 Constant Pressure
Compatible Cylinders
Clean, dry gas
Wet/rich gas
Dirty/variable streams
Custody transfer metering
High-accuracy applications
PLC-controlled facilities
Heated Gas Sampler
Essentials™ or GSS-4 · SC Cylinder or CP-2 Cylinder
When ambient temperature or near-dew-point gas conditions threaten sample integrity, a Welker heated enclosure provides complete protection. Either sampler is installed inside a thermostatically controlled, weatherproof enclosure with your choice of cylinder — maintaining optimal operating temperatures year-round.
Key Features
- Thermostatically controlled heating — consistent sample temperature
- Weatherproof enclosure for dust, moisture, and corrosion protection
- Prevents liquid dropout in near-dew-point applications
- Choice of Essentials™ or GSS-4PM sampler installed inside
- Compatible with both CP-2 and SC cylinder types
- Required for gas at or near its hydrocarbon dew point
Compatible Cylinders
SC Single Cavity
CP-2 Constant Pressure
Compatible Cylinders
Any gas condition
High-value custody transfer
Cylinder Selection
Choosing the Right Sample Cylinder
The sample container is as critical as the sampler. Select the cylinder that matches your gas composition and transport requirements.
CP-2 Constant Pressure Cylinder
Floating Piston Design · All Gas Types
The preferred cylinder for wet, rich, or near-dew-point natural gas. A floating piston maintains constant pressure on the sample throughout transport, preventing phase change and liquid dropout — preserving the original gas composition from pipeline to laboratory.
- Fresh Sample System™ — auto-purge before every cycle
- API 14.1 compliant flow-through sample path
- Pneumatically actuated — no external power required
- Ideal for remote and unmanned installations
- Low maintenance, field-proven construction
- Available in multiple volumes; insulated carrying cases available
SC Single Cavity Cylinder
DOT 3E Certified · Clean, Dry Gas
The economical choice for clean, dry, single-phase natural gas. A DOT 3E-certified fixed-volume cylinder built for straightforward gas sample collection and laboratory transport where phase stability is not a concern.
- DOT 3E certified for safe natural gas sample transport
- Simple, robust construction — lowest cost per cylinder
- Best suited for clean, dry, single-phase gas streams only
- Cylinder cleaning kits and dedicated cleaner stations available
- Cylinder carrying cases available for safe field transport
Side-by-Side Comparison
System Comparison
Match system capabilities against your application specifications to confirm the right configuration.
| Specification | Essentials™ + SC or CP-2 | GSS-4PM + SC or CP-2 | Heated Enclosure + SC or CP-2 |
|---|---|---|---|
| API 14.1 Compliant | ✔ Yes | ✔ Yes | ✔ Yes |
| Clean / Dry Gas | ✔ Optimized | ✔ Excellent | ✔ Excellent |
| Wet / Rich Gas | ✗ Not recommended | ✔ With LE-2SSKO option | ✔ Best option |
| Near Dew Point Gas | ✗ | — Marginal | ✔ Required config |
| Cold / Sub-Zero Climate | ✗ Not recommended | ✗ Not recommended | ✔ Designed for this |
| CP-2 Cylinder Compatible | ✔ | ✔ | ✔ |
| SC Cylinder Compatible | ✔ | ✔ | ✔ |
| External Power Required | No — fully pneumatic | Optional (solenoid) | Yes — heating required |
| PLC / Signal Control | — | ✔ Optional | ✔ Optional |
| Remote / Unmanned Sites | ✔ Ideal | ✔ With battery ctrl | ✔ With heated enclosure |
| Maintenance Frequency | Low | Low – Moderate | Low – Moderate |
Ready to Configure Your Sampling System?
Our application engineers will help you select the right sampler, cylinder, and accessories for your gas stream, site conditions, and regulatory requirements.
