FITOK 3DSS-FNS8-A 3-Valve Direct Mount Manifold, 1/2 in. NPT

3DSS-FNS8-A is a FITOK 3-valve direct mount instrument manifold in 316 stainless steel with a 1/2 in. female NPT process connection. The catalog lists 6,000 psig (414 bar) and -65 F to 450 F (-54 C to 232 C) with PTFE packing, for a differential pressure transmitter with a coplanar flange.

Isolate, equalize and vent a transmitter in one block

A 3-valve manifold combines two block (isolate) valves and one equalizing valve in a single body. The catalog describes this model as a direct mount design for a coplanar pressure transmitter such as the Rosemount type, so the manifold bolts straight to the transmitter and the process lines connect to the other side. Fewer joints than a built-up arrangement of separate valves mean fewer leak points.

The catalog color-codes the handles: black for isolate, red for vent and green for equalize. In the code, 3D is the 3-valve direct mount series, SS is 316 stainless steel, FNS8 is the 1/2 in. female NPT process connection and A is the angle layout described on page C-17; the suffix -A-P would add a vent with plug.

Supplied with the manifold

• Two PTFE sealing rings for the transmitter flange face.
• Four 7/16 in. UNF x 1.75 in. bolts for mounting.
• Four mounting holes of 0.47 in. (12.0 mm) diameter and two M10 threaded holes as shown in the dimension drawing.
• Handles in black, red and green to separate isolate, vent and equalize functions.

Technical specification

Specification of 3DSS-FNS8-A

Choosing a manifold for a transmitter

First decide on the number of valves. A 2-valve manifold only isolates; a 3-valve manifold adds an equalizing valve so that the transmitter zero can be checked; a 5-valve version adds bleed or vent valves for gas or steam. This code is a 3-valve type for general differential pressure use.

Next confirm the interface. The catalog states that this model is for coplanar flange transmitters, so it will not suit transmitters with a traditional flange. Compare the bolt pattern in the drawing with the transmitter flange before ordering.

The -A-P variant adds a vent with a plug, which makes the manifold fully open at 9.06 in. (230.0 mm) wide. Choose it when the transmitter must be vented during maintenance.

Commissioning order

Mount the manifold to the transmitter using the supplied PTFE rings and bolts, tightening in a cross pattern. Connect the process lines, close the equalizer, open both isolating valves and then check for leaks.

To zero the transmitter, close both isolating valves, open the equalizing valve, read the zero and reverse the sequence. Never leave the equalizing valve open while both isolators are open, as the transmitter then sees no differential.

Where manifolds are used

General engineering note: 3-valve manifolds are standard on flow, level and differential pressure transmitters in oil, gas, power and desalination plants in Oman and the GCC. A 316 stainless steel body is chosen for corrosion resistance in marine atmospheres. Check process compatibility and any plant standard before ordering.

Related FITOK items

The catalog also includes gauge valves, 2-valve and 5-valve manifolds and traditional-flange manifolds. FITOK needle valves, ball valves and tube fittings for the impulse lines can be quoted at the same time.

Frequently asked questions

What does the 3-valve manifold do?

It lets the operator isolate the transmitter from the process, equalize pressure across it and vent it for calibration.

Which transmitters does this model suit?

The catalog says it is designed for coplanar pressure transmitters, such as the Rosemount coplanar type.

What is included with the manifold?

Two PTFE sealing rings and four 7/16 in. UNF x 1.75 in. bolts are listed with the model.

What do the handle colors mean?

Black is isolate, red is vent and green is equalize.

Is Seven Star LLC a FITOK distributor?

No. Seven Star LLC is an independent supplier in Muscat that sources FITOK products on request.

Documents and quotation

Download the official FITOK datasheet and manual for 3DSS-FNS8-A from this page. As an independent supplier based in Muscat, Seven Star LLC supplies FITOK items on request: use the quote form with the quantity you need. Check every value in the documents against your own specification before you order. Browse similar items in the category.