Plastic Needle Valves
Precision flow adjustment in globe and angle patterns, for corrosive and high-purity service.
PVCCPVCPPPVDF
00Marquest Scientific · Thermoplastic fluid handling
Engineered for critical fluids.
Needle valves, instrument isolators, laboratory fixtures and DI-water guns, molded in PVC, CPVC, polypropylene and PVDF by a family-owned manufacturer in Orange County, California.
- 1 ID ring · white
- 2 Handle
- 3 Cap (bonnet)
- 4 Panel nut
- 5 Flare connection
- 6 Body — PVDF
Part no.NG-375-F-PVD
PureFlare™
Globe pattern · 3/8" flare
View
01Product lines
Browse by product line.
Browse 104 part numbers
Instrument Isolators
Diaphragm isolators that keep gauges and transmitters out of contact with aggressive media.
PVCCPVCPPNat PPPVDF
3 series
Laboratory Fixtures
DI-water faucets, turrets and base fixtures for laboratory casework.
PVCNat PPPVDF
5 series
Aquis™ Guns
PVDF guns for DI water, chemical dispensing and nitrogen drying.
PVDF
5 series
Vacuum Breakers
Atmospheric vacuum breakers that protect supply lines from back-siphonage.
PVCNat PPPVDF
1 series
- Atmospheric Vacuum Breakers
Coiled Tube Systems
Coiled tubing and assemblies in polyurethane and fluoropolymers.
PolyurethaneFEPPFA
2 series
- Coiled Tube Systems
- Coiled Tube
02Specify by material
Start with your chemistry.
Pick the body material your process calls for and see a real part made in it, with every product line we build in that material.
PVDF
477 part numbers
Ultra-pure fluoropolymer with exceptional chemical resistance.
Outstanding resistance to aggressive acids, halogens, and oxidizers with very low extractables. The premium material for ultrapure and aggressive chemical environments — widely accepted in semiconductor and pharmaceutical applications.
- Semiconductor wet-bench and wafer rinse
- Pharmaceutical and ultrapure water
- Aggressive acid and oxidizer service
Built in PVDF
- TUFF GUARD™ Isolators173
- Laboratory Fixtures170
- Mini TUFF GUARD™ Isolators66
- Aquis™ Guns40
- Repair Kits10
- Throttle Master™ Needle Valves6
- L Series Needle Valves6
- Throttle Master™ PureFlare™6
Section A–A · Mini TUFF GUARD™ isolator
03How isolation works
The gauge never touches the chemistry.
Corrosive media destroy instruments, and instruments can contaminate high-purity media. An isolator puts a diaphragm between the two, so each side only sees what it was built for.
- 1
Process connection
The body connects to your line. With the diaphragm, it is everything the process media touches.
- 2
Diaphragm
A flexible membrane carries process pressure across without letting the media through.
- 3
Instrument connection
The gauge, transmitter or switch mounts on the fill-fluid side, isolated from the chemistry it measures.
Which isolator?
Assembly filling serviceTUFF GUARD™1,036 part nos.
- Body
- PVC, CPVC, PP, PVDF
- Diaphragm
- Modified PTFE, FKM or EPDM
- Process connection
- 1/4" or 1/2" FNPT or socket
- Max pressure
- 250 psi · PP 240 psi
Mini TUFF GUARD™264 part nos.
- Body
- PVC, CPVC, Nat PP, PVDF
- Diaphragm
- PTFE/FKM composite
- Process connection
- 1/4" MNPT or FNPT, 1/2" MNPT
- Max pressure
- 250 psi · Nat PP 240 psi
04Markets
Where our parts run.
From semiconductor wet benches to municipal water plants, the application sets the material, and the material sets the part.
- 01
Semiconductor
High-purity flow control and gauge isolation for wet benches, wafer rinse, and aggressive chemistries — built from PVDF and fluoropolymers with no wetted metals.
Throttle Master™ PureFlare™ Needle ValvesTUFF GUARD™ Instrument IsolatorsAquis™ PVDF GunsLaboratory FixturesPVDFPTFEPFAFEP - 02
Pharmaceutical & Biotech
Contamination-free fluid handling for purified water, WFI, and reagent systems — high-purity PVDF and PTFE construction for regulated production environments.
Throttle Master™ PureFlare™ Needle ValvesTUFF GUARD™ Instrument IsolatorsLaboratory FixturesAquis™ PVDF GunsPVDFPTFENat PPPFA - 03
Chemical Processing
Corrosion-resistant valves and instrument isolators for aggressive acids, bases, and oxidizers — material selection matched to your chemistry and temperature.
PVCCPVCPPPVDFPTFEViton®EPDM - 04
Water & Wastewater Treatment
Durable thermoplastic flow control and gauge protection for municipal and industrial water systems, dosing, and analytical sampling.
PVCCPVCPPEPDM - 05
Laboratory & Analytical
Lab faucets, fixtures, and precision valves for DI/RO, ultrafiltered, and reagent-grade water — available in PVC, Natural Polypropylene, and high-purity PVDF.
PVCNat PPPVDFPTFE - 06
Food & Beverage
FDA-approved fill fluids and food-grade thermoplastic components for sanitary fluid handling and gauge isolation.
TUFF GUARD™ Instrument IsolatorsMini TUFF GUARD™ IsolatorsThrottle Master™ Needle ValvesLaboratory FixturesAquis™ PVDF GunsPVCPPPTFE
05Since the 1950s
Nearly seven decades of molding corrosion-resistant plastics.
- Late 1950s
Our founder brings the first reciprocating-screw injection molding machine to the U.S. from Ankerwerk of Nuremberg, the machine that made rigid PVC industrial parts moldable.
- 1964
With it, he molds the industry’s first all-plastic ball valve.
- 1978
Marquest Scientific is founded. Family owned and operated to this day.
- Today
Injection molding on 20- to 500-ton presses in Anaheim; assembly, testing, sales and administration in Costa Mesa, California.
Capabilities
The shop that builds our catalog can build your part.
06How to buy
Three ways to get Marquest parts.
Order online1,954of 1,954 part numbers with live pricing and checkout
Throttle Master™ · L Series · PureFlare™ · Repair Kits · TUFF GUARD™ · Mini TUFF GUARD™ · Aquis™ · Series LG · DURALINE
UPS and FedEx rates or your own collect account. Tax-exempt orders supported.
Search the catalog Distributors258distributor locations249 in the U.S. · 6 in Canada · France, Singapore and Taiwan
Buy through your existing supplier relationship and consolidate with the rest of your order.
Find a distributorTalk to sales714-491-9191Toll free 866-452-2349
Volume pricing, configurations not listed online, and custom parts built to your print.
Request a quoteEngineer’s toolkit
All resources- Valve CalculatorSize a needle valve from flow and pressure drop.
- MQCAD Center2D and 3D models in native and neutral formats.
- Fixture SelectorFind the right lab faucet for your service.
- Product LiteratureDatasheets, catalogs and drawings.
- Installation GuidesStep-by-step install and service instructions.
- ComplianceMaterial and regulatory documentation.