Revit API过滤管道系统类型

管道只能通过PipeType过滤出来类型属性，只能是系统族的类型属性。
管道实例过滤不能用族符号和族实例，要用Pipe

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using WinForm = System.Windows.Forms;

using Autodesk.Revit.UI;
using Autodesk.Revit.DB;
using Autodesk.Revit.Attributes;

using Autodesk.Revit.DB.Mechanical;
using Autodesk.Revit.UI.Selection;
using Autodesk.Revit.ApplicationServices;

using Autodesk.Revit.DB.Structure;
using Autodesk.Revit.DB.ExtensibleStorage;
using Autodesk.Revit.DB.Plumbing;
using Autodesk.Revit.DB.Architecture;

using System.Xml;

namespace RevitCodes
{

    [TransactionAttribute(Autodesk.Revit.Attributes.TransactionMode.Manual)]
    public class cmd : IExternalCommand
    {
        public Result Execute(ExternalCommandData commandData, ref string messages, ElementSet elements)
        {
            UIApplication uiApp = commandData.Application;
            Document doc = uiApp.ActiveUIDocument.Document;
            Selection sel = uiApp.ActiveUIDocument.Selection;

            Transaction ts = new Transaction(doc, "http://revit.5d6d.com");
            ts.Start();

            FilteredElementCollector collector = new FilteredElementCollector(doc);
            //此法可以只过滤系统类型
            collector.OfCategory(BuiltInCategory.OST_PipeCurves);
            foreach (Element el in collector.ToElements())
            {
                PipeType pipeType = el as PipeType;//管道类型有专有类型
                if (pipeType != null)
                    TaskDialog.Show("pipetype", pipeType.Name);
                FamilySymbol symbol = el as FamilySymbol;//即不是族符号
                if (symbol != null)
                    TaskDialog.Show("symbol", symbol.Name);
                FamilyInstance fi = el as FamilyInstance;//也不是族实例
                if(fi!=null)
                    TaskDialog.Show("fi", fi.Name);
                Pipe pipe = el as Pipe;
                if (pipe != null)
                    TaskDialog.Show("pipe", pipe.Name);
            }

            ts.Commit();

            return Result.Succeeded;
        }
    }
}

url:http://greatverve.cnblogs.com/p/api-pipe-type.html