Jerguson Gage & Valve
Series 300L Armored Level Gage
ANSI 300# Class · 750 PSI @ 100°F · Reflex & Transparent · Carbon Steel & 316LSS
The Jerguson Series 300L is the standard armored level gage for low-to-medium pressure service, rated to ANSI 300# class. The one-piece chamber is machined from bar stock — A696 Grade C carbon steel or A511 Grade TP316L stainless steel — eliminating weld seams from the pressure boundary. Bar stock covers, tempered borosilicate glass, and alloy steel hardware (A193 B7 / A194 2H) complete the assembly.
Recessed gasket seats in both the chamber and cover aid in positioning and retaining the gasket during assembly and field repair. Available in reflex (prismatic) or transparent (flat) glass styles. Multi-section assemblies extend visible length to 124-3/4". The Series 300L is a direct retrofit replacement for the older Jerguson Series 12 and Series 5 gages.
Reflex & Transparent Styles Shown.
Max Pressure
750 PSI @ 100°F (CS) · 720 PSI @ 100°F (316LSS)
Max Temperature
600°F (316°C)
Pressure Class
ANSI 300# Class
Glass
Reflex or transparent; tempered borosilicate per BS 3463, JIS B8211, DIN 7080/7081
Body Material
Carbon Steel (A696 Gr. C) or 316LSS (A511 TP316L)
Connections
1/2" or 3/4" NPT female standard; flanged or socket weld optional
Single-Section Visible Length
10-1/4" to 19-1/4"
Multi-Section Visible Length
Up to 124-3/4" (6 sections)
Replaces
Jerguson Series 12 and Series 5
Key Features
Pressure-Temperature Ratings (PSI)
| Body Material | 100°F | 200°F | 300°F | 400°F | 500°F | 600°F |
|---|---|---|---|---|---|---|
| Carbon Steel (A696 Gr. C) | 750 | 730 | 705 | 665 | 620 | 570 |
| 316LSS (A511 TP316L) | 720 | 680 | 640 | 600 | 560 | 510 |
Ratings are for the gage body. Borosilicate glass is rated to 600°F. Mica shield required for steam service above 406°F (208°C).
Single-Section Visible Lengths
Multi-Section Assemblies
| Number of Sections | Maximum Visible Length |
|---|---|
| 2 sections | 40-3/4" |
| 3 sections | 62-1/4" |
| 4 sections | 83-3/4" |
| 5 sections | 105-1/4" |
| 6 sections | 124-3/4" |
Multi-section assemblies use center valves between sections. Contact NCI for specific length configurations.
Reflex vs. Transparent Glass — Which to Choose?
Reflex (Prismatic) Glass
- →Liquid appears dark; vapor/gas appears bright silver
- →Self-illuminating — no external illuminator needed
- →Single glass piece — generally higher pressure rating
- →Best for water, steam, and clear process liquids
- →Mica shield available for steam and corrosive service
Transparent (Flat) Glass
- →Direct view of fluid color, clarity, and turbidity
- →Interface detection between two immiscible liquids
- →Illuminator recommended for dark or opaque fluids
- →Two glass pieces (front and back)
- →Best for colored fluids and interface detection
How to Order — Model Code
Specify series, glass type, visible length, body material, connection type, connection size, and any accessories. Example: 300L-R-14-1/4-C-N-3/4-M = Series 300L, reflex glass, 14-1/4" visible, carbon steel, 3/4" NPT, mica shield.
| Pos. | Field | Options |
|---|---|---|
| 1 | Series | 300L |
| 2 | Glass Type | R = Reflex · T = Transparent |
| 3 | Visible Length | Specified in inches (e.g., 10-1/4", 14-1/4") |
| 4 | Body Material | C = Carbon Steel · S = 316LSS |
| 5 | Connection Type | N = NPT female (std) · SW = Socket Weld · F = Flanged |
| 6 | Connection Size | 1/2" or 3/4" NPT; flange size as specified |
| 7 | Accessories | M = Mica Shield · I = Illuminator · D = Drain Plug |
Accessories & Options
Mica Shield
Protects glass from corrosive, caustic, or wet steam service. Required for steam above 406°F (208°C).
Illuminator
Recommended for transparent gages with dark or opaque fluids. Standard and explosion-proof configurations available.
Drain Plug
Plugged drain connection in the lower chamber for draining the gage body.
Isolation Valves
Jerguson gauge cocks and isolation valves for block-and-bleed service. See Jerguson Isolation Valves page.
Multi-Section Assemblies
Two to six gage sections connected with center valves for extended visible length up to 124-3/4".
Typical Applications
Process Vessel Level
General process vessel level indication in chemical, petrochemical, and refining applications up to 750 PSI.
Storage Tank Level
Visual level indication on storage tanks for liquids, chemicals, and hydrocarbons.
Boiler Water Level
Low-to-medium pressure boiler drum water level monitoring. Mica shield recommended for wet steam service.
Heat Exchanger Level
Monitor liquid level in heat exchanger shells and condensate pots.
Separator Level
Liquid level indication on gas/liquid separators and knockout drums.
Interface Detection
Transparent glass option for detecting the interface between two immiscible liquids (e.g., oil/water).
Retrofit — Series 12 / Series 5
Direct retrofit replacement for older Jerguson Series 12 and Series 5 gages. Same connection geometry.
ANSI 300# Class Service
Rated to ANSI 300# class pressure-temperature envelope. Suitable for a wide range of general process services.
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